GpuMemoryManager suggests values for renderer Contents Texture Managers' preferred memory limit.

BUG=123382
TEST=Manual


Review URL: http://codereview.chromium.org/10083056

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@134428 0039d316-1c4b-4281-b951-d872f2087c98

9 files changed, 365 insertions, 204 deletions

diff --git a/content/common/gpu/client/command_buffer_proxy_impl.cc b/content/common/gpu/client/command_buffer_proxy_impl.cc
index ce54be75..58ca3af 100644
--- a/content/common/gpu/client/command_buffer_proxy_impl.cc
+++ b/content/common/gpu/client/command_buffer_proxy_impl.cc
@@ -105,6 +105,8 @@ void CommandBufferProxyImpl::SetMemoryAllocationChangedCallback(
     const base::Callback<void(const GpuMemoryAllocationForRenderer&)>&
         callback) {
   memory_allocation_changed_callback_ = callback;
+  Send(new GpuCommandBufferMsg_SetClientHasMemoryAllocationChangedCallback(
+      route_id_, !memory_allocation_changed_callback_.is_null()));
 }
 
 void CommandBufferProxyImpl::OnSetMemoryAllocation(
diff --git a/content/common/gpu/client/webgraphicscontext3d_command_buffer_impl.cc b/content/common/gpu/client/webgraphicscontext3d_command_buffer_impl.cc
index 6fcce8a..cd06672 100644
--- a/content/common/gpu/client/webgraphicscontext3d_command_buffer_impl.cc
+++ b/content/common/gpu/client/webgraphicscontext3d_command_buffer_impl.cc
@@ -264,10 +264,6 @@ bool WebGraphicsContext3DCommandBufferImpl::MaybeInitializeGL(
     g_all_shared_contexts.Pointer()->insert(this);
   }
 
-  command_buffer_->SetMemoryAllocationChangedCallback(base::Bind(
-      &WebGraphicsContext3DCommandBufferImpl::OnMemoryAllocationChanged,
-      weak_ptr_factory_.GetWeakPtr()));
-
   visible_ = true;
   initialized_ = true;
   return true;
@@ -680,6 +676,14 @@ void WebGraphicsContext3DCommandBufferImpl::
     setMemoryAllocationChangedCallbackCHROMIUM(
         WebGraphicsMemoryAllocationChangedCallbackCHROMIUM* callback) {
   memory_allocation_changed_callback_ = callback;
+
+  if (callback)
+    command_buffer_->SetMemoryAllocationChangedCallback(base::Bind(
+        &WebGraphicsContext3DCommandBufferImpl::OnMemoryAllocationChanged,
+        weak_ptr_factory_.GetWeakPtr()));
+  else
+    command_buffer_->SetMemoryAllocationChangedCallback(
+        base::Callback<void(const GpuMemoryAllocationForRenderer&)>());
 }
 
 
diff --git a/content/common/gpu/gpu_command_buffer_stub.cc b/content/common/gpu/gpu_command_buffer_stub.cc
index b6f6d28..11deb70 100644
--- a/content/common/gpu/gpu_command_buffer_stub.cc
+++ b/content/common/gpu/gpu_command_buffer_stub.cc
@@ -58,7 +58,9 @@ GpuCommandBufferStub::GpuCommandBufferStub(
       route_id_(route_id),
       software_(software),
       last_flush_count_(0),
-      allocation_(GpuMemoryAllocation::INVALID_RESOURCE_SIZE, true, true),
+      allocation_(GpuMemoryAllocation::INVALID_RESOURCE_SIZE,
+                  GpuMemoryAllocation::kHasFrontbuffer |
+                  GpuMemoryAllocation::kHasBackbuffer),
       parent_stub_for_initialization_(),
       parent_texture_for_initialization_(0),
       watchdog_(watchdog) {
@@ -130,6 +132,9 @@ bool GpuCommandBufferStub::OnMessageReceived(const IPC::Message& message) {
                         OnDiscardBackbuffer)
     IPC_MESSAGE_HANDLER(GpuCommandBufferMsg_EnsureBackbuffer,
                         OnEnsureBackbuffer)
+    IPC_MESSAGE_HANDLER(
+        GpuCommandBufferMsg_SetClientHasMemoryAllocationChangedCallback,
+        OnSetClientHasMemoryAllocationChangedCallback)
     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP()
 
@@ -588,6 +593,12 @@ void GpuCommandBufferStub::OnEnsureBackbuffer() {
       gfx::GLSurface::BUFFER_ALLOCATION_FRONT_AND_BACK);
 }
 
+void GpuCommandBufferStub::OnSetClientHasMemoryAllocationChangedCallback(
+    bool has_callback) {
+  client_has_memory_allocation_changed_callback_ = has_callback;
+  channel_->gpu_channel_manager()->gpu_memory_manager()->ScheduleManage();
+}
+
 void GpuCommandBufferStub::SendConsoleMessage(
     int32 id,
     const std::string& message) {
@@ -616,6 +627,11 @@ bool GpuCommandBufferStub::IsInSameContextShareGroup(
       static_cast<const GpuCommandBufferStub&>(other).context_group_;
 }
 
+bool GpuCommandBufferStub::
+    client_has_memory_allocation_changed_callback() const {
+  return client_has_memory_allocation_changed_callback_;
+}
+
 bool GpuCommandBufferStub::has_surface_state() const {
   return surface_state_ != NULL;
 }
diff --git a/content/common/gpu/gpu_command_buffer_stub.h b/content/common/gpu/gpu_command_buffer_stub.h
index 4f08818..ff6537e 100644
--- a/content/common/gpu/gpu_command_buffer_stub.h
+++ b/content/common/gpu/gpu_command_buffer_stub.h
@@ -57,6 +57,7 @@ class CONTENT_EXPORT GpuCommandBufferStubBase {
   virtual ~GpuCommandBufferStubBase() {}
 
   // Will not have surface state if this is an offscreen commandbuffer.
+  virtual bool client_has_memory_allocation_changed_callback() const = 0;
   virtual bool has_surface_state() const = 0;
   virtual const SurfaceState& surface_state() const = 0;
 
@@ -107,6 +108,7 @@ class GpuCommandBufferStub
   virtual bool Send(IPC::Message* msg) OVERRIDE;
 
   // GpuCommandBufferStubBase implementation:
+  virtual bool client_has_memory_allocation_changed_callback() const OVERRIDE;
   virtual bool has_surface_state() const OVERRIDE;
   virtual const GpuCommandBufferStubBase::SurfaceState& surface_state() const
       OVERRIDE;
@@ -198,6 +200,8 @@ class GpuCommandBufferStub
   void OnDiscardBackbuffer();
   void OnEnsureBackbuffer();
 
+  void OnSetClientHasMemoryAllocationChangedCallback(bool);
+
   void OnReschedule();
 
   void OnCommandProcessed();
@@ -221,6 +225,7 @@ class GpuCommandBufferStub
   gfx::GpuPreference gpu_preference_;
   int32 route_id_;
   bool software_;
+  bool client_has_memory_allocation_changed_callback_;
   uint32 last_flush_count_;
   scoped_ptr<GpuCommandBufferStubBase::SurfaceState> surface_state_;
   GpuMemoryAllocation allocation_;
diff --git a/content/common/gpu/gpu_memory_allocation.h b/content/common/gpu/gpu_memory_allocation.h
index b38fe832..3e11979 100644
--- a/content/common/gpu/gpu_memory_allocation.h
+++ b/content/common/gpu/gpu_memory_allocation.h
@@ -12,7 +12,6 @@
 // and assigned to the browser and renderer context.
 // They will change over time, given memory availability, and browser state.
 
-
 // Memory Allocation which will be assigned to the renderer context.
 struct GpuMemoryAllocationForRenderer {
   enum {
@@ -68,17 +67,24 @@ struct GpuMemoryAllocationForBrowser {
 // GpuMemoryManager.
 struct GpuMemoryAllocation : public GpuMemoryAllocationForRenderer,
                              public GpuMemoryAllocationForBrowser {
+  // Bitmap
+  enum BufferAllocation {
+    kHasNoBuffers = 0,
+    kHasFrontbuffer = 1,
+    kHasBackbuffer = 2
+  };
+
   GpuMemoryAllocation()
       : GpuMemoryAllocationForRenderer(),
         GpuMemoryAllocationForBrowser() {
   }
 
   GpuMemoryAllocation(size_t gpu_resource_size_in_bytes,
-                      bool suggest_have_backbuffer,
-                      bool suggest_have_frontbuffer)
+                      int allocationBitmap)
       : GpuMemoryAllocationForRenderer(gpu_resource_size_in_bytes,
-                                       suggest_have_backbuffer),
-        GpuMemoryAllocationForBrowser(suggest_have_frontbuffer) {
+            (allocationBitmap & kHasBackbuffer) == kHasBackbuffer),
+        GpuMemoryAllocationForBrowser(
+            (allocationBitmap & kHasFrontbuffer) == kHasFrontbuffer) {
   }
 
   bool operator==(const GpuMemoryAllocation& other) const {
diff --git a/content/common/gpu/gpu_memory_manager.cc b/content/common/gpu/gpu_memory_manager.cc
index 163ebf0..d174098 100644
--- a/content/common/gpu/gpu_memory_manager.cc
+++ b/content/common/gpu/gpu_memory_manager.cc
@@ -15,15 +15,6 @@
 
 namespace {
 
-// These are predefined values (in bytes) for
-// GpuMemoryAllocation::gpuResourceSizeInBytes.  Currently, the value is only
-// used to check if it is 0 or non-0.  In the future, these values will not
-// come from constants, but rather will be distributed dynamically.
-enum {
-  kResourceSizeNonHibernatedTab = 1,
-  kResourceSizeHibernatedTab = 0
-};
-
 bool IsInSameContextShareGroupAsAnyOf(
     const GpuCommandBufferStubBase* stub,
     const std::vector<GpuCommandBufferStubBase*>& stubs) {
@@ -35,6 +26,14 @@ bool IsInSameContextShareGroupAsAnyOf(
   return false;
 }
 
+void AssignMemoryAllocations(std::vector<GpuCommandBufferStubBase*>& stubs,
+    GpuMemoryAllocation allocation) {
+  for (std::vector<GpuCommandBufferStubBase*>::iterator it = stubs.begin();
+      it != stubs.end(); ++it) {
+    (*it)->SetMemoryAllocation(allocation);
+  }
+}
+
 }
 
 GpuMemoryManager::GpuMemoryManager(GpuMemoryManagerClient* client,
@@ -100,14 +99,6 @@ void GpuMemoryManager::ScheduleManage() {
 //  1. Find the most visible context-with-a-surface within each
 //     context-without-a-surface's share group, and inherit its visibilty.
 void GpuMemoryManager::Manage() {
-  // Set up three allocation values for the three possible stub states
-  const GpuMemoryAllocation all_buffers_allocation(
-      kResourceSizeNonHibernatedTab, true, true);
-  const GpuMemoryAllocation front_buffers_allocation(
-      kResourceSizeNonHibernatedTab, false, true);
-  const GpuMemoryAllocation no_buffers_allocation(
-      kResourceSizeHibernatedTab, false, false);
-
   manage_scheduled_ = false;
 
   // Create stub lists by separating out the two types received from client
@@ -120,6 +111,8 @@ void GpuMemoryManager::Manage() {
     for (std::vector<GpuCommandBufferStubBase*>::iterator it = stubs.begin();
         it != stubs.end(); ++it) {
       GpuCommandBufferStubBase* stub = *it;
+      if (!stub->client_has_memory_allocation_changed_callback())
+        continue;
       if (stub->has_surface_state())
         stubs_with_surface.push_back(stub);
       else
@@ -136,37 +129,73 @@ void GpuMemoryManager::Manage() {
          stubs_with_surface.end());
 
   // Separate stubs into memory allocation sets.
-  std::vector<GpuCommandBufferStubBase*> all_buffers, front_buffers, no_buffers;
+  std::vector<GpuCommandBufferStubBase*> stubs_with_surface_foreground,
+                                         stubs_with_surface_background,
+                                         stubs_with_surface_hibernated,
+                                         stubs_without_surface_foreground,
+                                         stubs_without_surface_background,
+                                         stubs_without_surface_hibernated;
 
   for (size_t i = 0; i < stubs_with_surface.size(); ++i) {
     GpuCommandBufferStubBase* stub = stubs_with_surface[i];
     DCHECK(stub->has_surface_state());
-    if (stub->surface_state().visible) {
-      all_buffers.push_back(stub);
-      stub->SetMemoryAllocation(all_buffers_allocation);
-    } else if (i < max_surfaces_with_frontbuffer_soft_limit_) {
-      front_buffers.push_back(stub);
-      stub->SetMemoryAllocation(front_buffers_allocation);
-    } else {
-      no_buffers.push_back(stub);
-      stub->SetMemoryAllocation(no_buffers_allocation);
-    }
+    if (stub->surface_state().visible)
+      stubs_with_surface_foreground.push_back(stub);
+    else if (i < max_surfaces_with_frontbuffer_soft_limit_)
+      stubs_with_surface_background.push_back(stub);
+    else
+      stubs_with_surface_hibernated.push_back(stub);
   }
-
-  // Now, go through the stubs without surfaces and deduce visibility using the
-  // visibility of stubs which are in the same context share group.
   for (std::vector<GpuCommandBufferStubBase*>::const_iterator it =
       stubs_without_surface.begin(); it != stubs_without_surface.end(); ++it) {
     GpuCommandBufferStubBase* stub = *it;
     DCHECK(!stub->has_surface_state());
-    if (IsInSameContextShareGroupAsAnyOf(stub, all_buffers)) {
-      stub->SetMemoryAllocation(all_buffers_allocation);
-    } else if (IsInSameContextShareGroupAsAnyOf(stub, front_buffers)) {
-      stub->SetMemoryAllocation(front_buffers_allocation);
-    } else {
-      stub->SetMemoryAllocation(no_buffers_allocation);
-    }
+
+    // Stubs without surfaces have deduced allocation state using the state
+    // of surface stubs which are in the same context share group.
+    if (IsInSameContextShareGroupAsAnyOf(stub, stubs_with_surface_foreground))
+      stubs_without_surface_foreground.push_back(stub);
+    else if (IsInSameContextShareGroupAsAnyOf(
+        stub, stubs_with_surface_background))
+      stubs_without_surface_background.push_back(stub);
+    else
+      stubs_without_surface_hibernated.push_back(stub);
   }
+
+  // Calculate memory allocation size in bytes given to each stub, by sharing
+  // global limit equally among those that need it.
+  size_t num_stubs_need_mem = stubs_with_surface_foreground.size() +
+                              stubs_without_surface_foreground.size() +
+                              stubs_without_surface_background.size();
+  size_t base_allocation_size = kMinimumAllocationForTab * num_stubs_need_mem;
+  size_t bonus_allocation = 0;
+  if (base_allocation_size < kMaximumAllocationForTabs &&
+      !stubs_with_surface_foreground.empty())
+    bonus_allocation = (kMaximumAllocationForTabs - base_allocation_size) /
+                           stubs_with_surface_foreground.size();
+
+  // Now give out allocations to everyone.
+  AssignMemoryAllocations(stubs_with_surface_foreground,
+      GpuMemoryAllocation(kMinimumAllocationForTab + bonus_allocation,
+          GpuMemoryAllocation::kHasFrontbuffer |
+          GpuMemoryAllocation::kHasBackbuffer));
+
+  AssignMemoryAllocations(stubs_with_surface_background,
+      GpuMemoryAllocation(0, GpuMemoryAllocation::kHasFrontbuffer));
+
+  AssignMemoryAllocations(stubs_with_surface_hibernated,
+      GpuMemoryAllocation(0, GpuMemoryAllocation::kHasNoBuffers));
+
+  AssignMemoryAllocations(stubs_without_surface_foreground,
+      GpuMemoryAllocation(kMinimumAllocationForTab,
+          GpuMemoryAllocation::kHasNoBuffers));
+
+  AssignMemoryAllocations(stubs_without_surface_background,
+      GpuMemoryAllocation(kMinimumAllocationForTab,
+          GpuMemoryAllocation::kHasNoBuffers));
+
+  AssignMemoryAllocations(stubs_without_surface_hibernated,
+      GpuMemoryAllocation(0, GpuMemoryAllocation::kHasNoBuffers));
 }
 
 #endif
diff --git a/content/common/gpu/gpu_memory_manager.h b/content/common/gpu/gpu_memory_manager.h
index 51f6930..0a84ec4 100644
--- a/content/common/gpu/gpu_memory_manager.h
+++ b/content/common/gpu/gpu_memory_manager.h
@@ -28,6 +28,23 @@ class CONTENT_EXPORT GpuMemoryManager {
  public:
   enum { kDefaultMaxSurfacesWithFrontbufferSoftLimit = 8 };
 
+  // These are predefined values (in bytes) for
+  // GpuMemoryAllocation::gpuResourceSizeInBytes.
+  // Maximum Allocation for all tabs is a soft limit that can be exceeded
+  // during the time it takes for renderers to respect new allocations,
+  // including when switching tabs or opening a new window.
+  // To alleviate some pressure, we decrease our desired limit by "one tabs'
+  // worth" of memory.
+  enum {
+#if defined(OS_ANDROID)
+    kMinimumAllocationForTab = 32 * 1024 * 1024,
+    kMaximumAllocationForTabs = 64 * 1024 * 1024,
+#else
+    kMinimumAllocationForTab = 64 * 1024 * 1024,
+    kMaximumAllocationForTabs = 512 * 1024 * 1024 - kMinimumAllocationForTab,
+#endif
+  };
+
   GpuMemoryManager(GpuMemoryManagerClient* client,
                    size_t max_surfaces_with_frontbuffer_soft_limit);
   ~GpuMemoryManager();
diff --git a/content/common/gpu/gpu_memory_manager_unittest.cc b/content/common/gpu/gpu_memory_manager_unittest.cc
index 501e481..3e56203 100644
--- a/content/common/gpu/gpu_memory_manager_unittest.cc
+++ b/content/common/gpu/gpu_memory_manager_unittest.cc
@@ -23,6 +23,9 @@ class FakeCommandBufferStub : public GpuCommandBufferStubBase {
       : surface_state_(surface_id, visible, last_used_time) {
   }
 
+  virtual bool client_has_memory_allocation_changed_callback() const {
+    return true;
+  }
   virtual bool has_surface_state() const {
     return surface_state_.surface_id != 0;
   }
@@ -49,6 +52,9 @@ class FakeCommandBufferStubWithoutSurface : public GpuCommandBufferStubBase {
   FakeCommandBufferStubWithoutSurface() {
   }
 
+  virtual bool client_has_memory_allocation_changed_callback() const {
+    return true;
+  }
   virtual bool has_surface_state() const {
     return false;
   }
@@ -100,11 +106,51 @@ class GpuMemoryManagerTest : public testing::Test {
     return surface_id_++;
   }
 
-  static bool is_more_important(GpuCommandBufferStubBase* lhs,
-                                GpuCommandBufferStubBase* rhs) {
+  static bool IsMoreImportant(GpuCommandBufferStubBase* lhs,
+                              GpuCommandBufferStubBase* rhs) {
     return GpuMemoryManager::StubWithSurfaceComparator()(lhs, rhs);
   }
 
+  static bool IsAllocationForegroundForSurfaceYes(
+      const GpuMemoryAllocation& alloc) {
+    return alloc.suggest_have_frontbuffer &&
+           alloc.suggest_have_backbuffer &&
+           alloc.gpu_resource_size_in_bytes >=
+               GpuMemoryManager::kMinimumAllocationForTab;
+  }
+  static bool IsAllocationBackgroundForSurfaceYes(
+      const GpuMemoryAllocation& alloc) {
+    return alloc.suggest_have_frontbuffer &&
+           !alloc.suggest_have_backbuffer &&
+           alloc.gpu_resource_size_in_bytes == 0;
+  }
+  static bool IsAllocationHibernatedForSurfaceYes(
+      const GpuMemoryAllocation& alloc) {
+    return !alloc.suggest_have_frontbuffer &&
+           !alloc.suggest_have_backbuffer &&
+           alloc.gpu_resource_size_in_bytes == 0;
+  }
+  static bool IsAllocationForegroundForSurfaceNo(
+      const GpuMemoryAllocation& alloc) {
+    return !alloc.suggest_have_frontbuffer &&
+           !alloc.suggest_have_backbuffer &&
+           alloc.gpu_resource_size_in_bytes ==
+               GpuMemoryManager::kMinimumAllocationForTab;
+  }
+  static bool IsAllocationBackgroundForSurfaceNo(
+      const GpuMemoryAllocation& alloc) {
+    return !alloc.suggest_have_frontbuffer &&
+           !alloc.suggest_have_backbuffer &&
+           alloc.gpu_resource_size_in_bytes ==
+               GpuMemoryManager::kMinimumAllocationForTab;
+  }
+  static bool IsAllocationHibernatedForSurfaceNo(
+      const GpuMemoryAllocation& alloc) {
+    return !alloc.suggest_have_frontbuffer &&
+           !alloc.suggest_have_backbuffer &&
+           alloc.gpu_resource_size_in_bytes == 0;
+  }
+
   void Manage() {
     memory_manager_.Manage();
   }
@@ -126,50 +172,50 @@ TEST_F(GpuMemoryManagerTest, ComparatorTests) {
                         stub_false3(GenerateUniqueSurfaceId(), false, newest_);
 
   // Should never be more important than self:
-  EXPECT_FALSE(is_more_important(&stub_true1, &stub_true1));
-  EXPECT_FALSE(is_more_important(&stub_true2, &stub_true2));
-  EXPECT_FALSE(is_more_important(&stub_true3, &stub_true3));
-  EXPECT_FALSE(is_more_important(&stub_false1, &stub_false1));
-  EXPECT_FALSE(is_more_important(&stub_false2, &stub_false2));
-  EXPECT_FALSE(is_more_important(&stub_false3, &stub_false3));
+  EXPECT_FALSE(IsMoreImportant(&stub_true1, &stub_true1));
+  EXPECT_FALSE(IsMoreImportant(&stub_true2, &stub_true2));
+  EXPECT_FALSE(IsMoreImportant(&stub_true3, &stub_true3));
+  EXPECT_FALSE(IsMoreImportant(&stub_false1, &stub_false1));
+  EXPECT_FALSE(IsMoreImportant(&stub_false2, &stub_false2));
+  EXPECT_FALSE(IsMoreImportant(&stub_false3, &stub_false3));
 
   // Visible should always be more important than non visible:
-  EXPECT_TRUE(is_more_important(&stub_true1, &stub_false1));
-  EXPECT_TRUE(is_more_important(&stub_true1, &stub_false2));
-  EXPECT_TRUE(is_more_important(&stub_true1, &stub_false3));
-  EXPECT_TRUE(is_more_important(&stub_true2, &stub_false1));
-  EXPECT_TRUE(is_more_important(&stub_true2, &stub_false2));
-  EXPECT_TRUE(is_more_important(&stub_true2, &stub_false3));
-  EXPECT_TRUE(is_more_important(&stub_true3, &stub_false1));
-  EXPECT_TRUE(is_more_important(&stub_true3, &stub_false2));
-  EXPECT_TRUE(is_more_important(&stub_true3, &stub_false3));
+  EXPECT_TRUE(IsMoreImportant(&stub_true1, &stub_false1));
+  EXPECT_TRUE(IsMoreImportant(&stub_true1, &stub_false2));
+  EXPECT_TRUE(IsMoreImportant(&stub_true1, &stub_false3));
+  EXPECT_TRUE(IsMoreImportant(&stub_true2, &stub_false1));
+  EXPECT_TRUE(IsMoreImportant(&stub_true2, &stub_false2));
+  EXPECT_TRUE(IsMoreImportant(&stub_true2, &stub_false3));
+  EXPECT_TRUE(IsMoreImportant(&stub_true3, &stub_false1));
+  EXPECT_TRUE(IsMoreImportant(&stub_true3, &stub_false2));
+  EXPECT_TRUE(IsMoreImportant(&stub_true3, &stub_false3));
 
   // Not visible should never be more important than visible:
-  EXPECT_FALSE(is_more_important(&stub_false1, &stub_true1));
-  EXPECT_FALSE(is_more_important(&stub_false1, &stub_true2));
-  EXPECT_FALSE(is_more_important(&stub_false1, &stub_true3));
-  EXPECT_FALSE(is_more_important(&stub_false2, &stub_true1));
-  EXPECT_FALSE(is_more_important(&stub_false2, &stub_true2));
-  EXPECT_FALSE(is_more_important(&stub_false2, &stub_true3));
-  EXPECT_FALSE(is_more_important(&stub_false3, &stub_true1));
-  EXPECT_FALSE(is_more_important(&stub_false3, &stub_true2));
-  EXPECT_FALSE(is_more_important(&stub_false3, &stub_true3));
+  EXPECT_FALSE(IsMoreImportant(&stub_false1, &stub_true1));
+  EXPECT_FALSE(IsMoreImportant(&stub_false1, &stub_true2));
+  EXPECT_FALSE(IsMoreImportant(&stub_false1, &stub_true3));
+  EXPECT_FALSE(IsMoreImportant(&stub_false2, &stub_true1));
+  EXPECT_FALSE(IsMoreImportant(&stub_false2, &stub_true2));
+  EXPECT_FALSE(IsMoreImportant(&stub_false2, &stub_true3));
+  EXPECT_FALSE(IsMoreImportant(&stub_false3, &stub_true1));
+  EXPECT_FALSE(IsMoreImportant(&stub_false3, &stub_true2));
+  EXPECT_FALSE(IsMoreImportant(&stub_false3, &stub_true3));
 
   // Newer should always be more important than older:
-  EXPECT_TRUE(is_more_important(&stub_true2, &stub_true1));
-  EXPECT_TRUE(is_more_important(&stub_true3, &stub_true1));
-  EXPECT_TRUE(is_more_important(&stub_true3, &stub_true2));
-  EXPECT_TRUE(is_more_important(&stub_false2, &stub_false1));
-  EXPECT_TRUE(is_more_important(&stub_false3, &stub_false1));
-  EXPECT_TRUE(is_more_important(&stub_false3, &stub_false2));
+  EXPECT_TRUE(IsMoreImportant(&stub_true2, &stub_true1));
+  EXPECT_TRUE(IsMoreImportant(&stub_true3, &stub_true1));
+  EXPECT_TRUE(IsMoreImportant(&stub_true3, &stub_true2));
+  EXPECT_TRUE(IsMoreImportant(&stub_false2, &stub_false1));
+  EXPECT_TRUE(IsMoreImportant(&stub_false3, &stub_false1));
+  EXPECT_TRUE(IsMoreImportant(&stub_false3, &stub_false2));
 
   // Older should never be more important than newer:
-  EXPECT_FALSE(is_more_important(&stub_true1, &stub_true2));
-  EXPECT_FALSE(is_more_important(&stub_true1, &stub_true3));
-  EXPECT_FALSE(is_more_important(&stub_true2, &stub_true3));
-  EXPECT_FALSE(is_more_important(&stub_false1, &stub_false2));
-  EXPECT_FALSE(is_more_important(&stub_false1, &stub_false3));
-  EXPECT_FALSE(is_more_important(&stub_false2, &stub_false3));
+  EXPECT_FALSE(IsMoreImportant(&stub_true1, &stub_true2));
+  EXPECT_FALSE(IsMoreImportant(&stub_true1, &stub_true3));
+  EXPECT_FALSE(IsMoreImportant(&stub_true2, &stub_true3));
+  EXPECT_FALSE(IsMoreImportant(&stub_false1, &stub_false2));
+  EXPECT_FALSE(IsMoreImportant(&stub_false1, &stub_false3));
+  EXPECT_FALSE(IsMoreImportant(&stub_false2, &stub_false3));
 }
 
 // Test GpuMemoryManager::Manage basic functionality.
@@ -185,10 +231,8 @@ TEST_F(GpuMemoryManagerTest, TestManageBasicFunctionality) {
   client_.stubs_.push_back(&stub2);
 
   Manage();
-  EXPECT_EQ(stub1.allocation_.suggest_have_frontbuffer, true);
-  EXPECT_EQ(stub1.allocation_.suggest_have_backbuffer, true);
-  EXPECT_EQ(stub2.allocation_.suggest_have_frontbuffer, true);
-  EXPECT_EQ(stub2.allocation_.suggest_have_backbuffer, false);
+  EXPECT_TRUE(IsAllocationForegroundForSurfaceYes(stub1.allocation_));
+  EXPECT_TRUE(IsAllocationBackgroundForSurfaceYes(stub2.allocation_));
 
   // Test stubs without surface, with share group of 1 stub.
   FakeCommandBufferStubWithoutSurface stub3, stub4;
@@ -198,8 +242,10 @@ TEST_F(GpuMemoryManagerTest, TestManageBasicFunctionality) {
   client_.stubs_.push_back(&stub4);
 
   Manage();
-  EXPECT_EQ(stub1.allocation_, stub3.allocation_);
-  EXPECT_EQ(stub2.allocation_, stub4.allocation_);
+  EXPECT_TRUE(IsAllocationForegroundForSurfaceYes(stub1.allocation_));
+  EXPECT_TRUE(IsAllocationBackgroundForSurfaceYes(stub2.allocation_));
+  EXPECT_TRUE(IsAllocationForegroundForSurfaceNo(stub3.allocation_));
+  EXPECT_TRUE(IsAllocationBackgroundForSurfaceNo(stub4.allocation_));
 
   // Test stub without surface, with share group of multiple stubs.
   FakeCommandBufferStubWithoutSurface stub5;
@@ -208,7 +254,7 @@ TEST_F(GpuMemoryManagerTest, TestManageBasicFunctionality) {
   client_.stubs_.push_back(&stub5);
 
   Manage();
-  EXPECT_EQ(stub1.allocation_, stub5.allocation_);
+  EXPECT_TRUE(IsAllocationForegroundForSurfaceNo(stub4.allocation_));
 }
 
 // Test GpuMemoryManager::Manage functionality: changing visibility.
@@ -234,25 +280,21 @@ TEST_F(GpuMemoryManagerTest, TestManageChangingVisibility) {
   client_.stubs_.push_back(&stub5);
 
   Manage();
-  EXPECT_EQ(stub1.allocation_.suggest_have_frontbuffer, true);
-  EXPECT_EQ(stub1.allocation_.suggest_have_backbuffer, true);
-  EXPECT_EQ(stub2.allocation_.suggest_have_frontbuffer, true);
-  EXPECT_EQ(stub2.allocation_.suggest_have_backbuffer, false);
-  EXPECT_EQ(stub1.allocation_, stub3.allocation_);
-  EXPECT_EQ(stub2.allocation_, stub4.allocation_);
-  EXPECT_EQ(stub1.allocation_, stub5.allocation_);
+  EXPECT_TRUE(IsAllocationForegroundForSurfaceYes(stub1.allocation_));
+  EXPECT_TRUE(IsAllocationBackgroundForSurfaceYes(stub2.allocation_));
+  EXPECT_TRUE(IsAllocationForegroundForSurfaceNo(stub3.allocation_));
+  EXPECT_TRUE(IsAllocationBackgroundForSurfaceNo(stub4.allocation_));
+  EXPECT_TRUE(IsAllocationForegroundForSurfaceNo(stub5.allocation_));
 
   stub1.surface_state_.visible = false;
   stub2.surface_state_.visible = true;
 
   Manage();
-  EXPECT_EQ(stub1.allocation_.suggest_have_frontbuffer, true);
-  EXPECT_EQ(stub1.allocation_.suggest_have_backbuffer, false);
-  EXPECT_EQ(stub2.allocation_.suggest_have_frontbuffer, true);
-  EXPECT_EQ(stub2.allocation_.suggest_have_backbuffer, true);
-  EXPECT_EQ(stub1.allocation_, stub3.allocation_);
-  EXPECT_EQ(stub2.allocation_, stub4.allocation_);
-  EXPECT_EQ(stub2.allocation_, stub5.allocation_);
+  EXPECT_TRUE(IsAllocationBackgroundForSurfaceYes(stub1.allocation_));
+  EXPECT_TRUE(IsAllocationForegroundForSurfaceYes(stub2.allocation_));
+  EXPECT_TRUE(IsAllocationBackgroundForSurfaceNo(stub3.allocation_));
+  EXPECT_TRUE(IsAllocationForegroundForSurfaceNo(stub4.allocation_));
+  EXPECT_TRUE(IsAllocationForegroundForSurfaceNo(stub5.allocation_));
 }
 
 // Test GpuMemoryManager::Manage functionality: Test more than threshold number
@@ -280,17 +322,13 @@ TEST_F(GpuMemoryManagerTest, TestManageManyVisibleStubs) {
   client_.stubs_.push_back(&stub7);
 
   Manage();
-  EXPECT_EQ(stub1.allocation_.suggest_have_frontbuffer, true);
-  EXPECT_EQ(stub1.allocation_.suggest_have_backbuffer, true);
-  EXPECT_EQ(stub2.allocation_.suggest_have_frontbuffer, true);
-  EXPECT_EQ(stub2.allocation_.suggest_have_backbuffer, true);
-  EXPECT_EQ(stub3.allocation_.suggest_have_frontbuffer, true);
-  EXPECT_EQ(stub3.allocation_.suggest_have_backbuffer, true);
-  EXPECT_EQ(stub4.allocation_.suggest_have_frontbuffer, true);
-  EXPECT_EQ(stub4.allocation_.suggest_have_backbuffer, true);
-  EXPECT_EQ(stub5.allocation_, stub1.allocation_);
-  EXPECT_EQ(stub6.allocation_, stub2.allocation_);
-  EXPECT_EQ(stub7.allocation_, stub1.allocation_);
+  EXPECT_TRUE(IsAllocationForegroundForSurfaceYes(stub1.allocation_));
+  EXPECT_TRUE(IsAllocationForegroundForSurfaceYes(stub2.allocation_));
+  EXPECT_TRUE(IsAllocationForegroundForSurfaceYes(stub3.allocation_));
+  EXPECT_TRUE(IsAllocationForegroundForSurfaceYes(stub4.allocation_));
+  EXPECT_TRUE(IsAllocationForegroundForSurfaceNo(stub5.allocation_));
+  EXPECT_TRUE(IsAllocationForegroundForSurfaceNo(stub6.allocation_));
+  EXPECT_TRUE(IsAllocationForegroundForSurfaceNo(stub7.allocation_));
 }
 
 // Test GpuMemoryManager::Manage functionality: Test more than threshold number
@@ -318,17 +356,13 @@ TEST_F(GpuMemoryManagerTest, TestManageManyNotVisibleStubs) {
   client_.stubs_.push_back(&stub7);
 
   Manage();
-  EXPECT_EQ(stub1.allocation_.suggest_have_frontbuffer, true);
-  EXPECT_EQ(stub1.allocation_.suggest_have_backbuffer, false);
-  EXPECT_EQ(stub2.allocation_.suggest_have_frontbuffer, true);
-  EXPECT_EQ(stub2.allocation_.suggest_have_backbuffer, false);
-  EXPECT_EQ(stub3.allocation_.suggest_have_frontbuffer, true);
-  EXPECT_EQ(stub3.allocation_.suggest_have_backbuffer, false);
-  EXPECT_EQ(stub4.allocation_.suggest_have_frontbuffer, false);
-  EXPECT_EQ(stub4.allocation_.suggest_have_backbuffer, false);
-  EXPECT_EQ(stub5.allocation_, stub1.allocation_);
-  EXPECT_EQ(stub6.allocation_, stub4.allocation_);
-  EXPECT_EQ(stub7.allocation_, stub1.allocation_);
+  EXPECT_TRUE(IsAllocationBackgroundForSurfaceYes(stub1.allocation_));
+  EXPECT_TRUE(IsAllocationBackgroundForSurfaceYes(stub2.allocation_));
+  EXPECT_TRUE(IsAllocationBackgroundForSurfaceYes(stub3.allocation_));
+  EXPECT_TRUE(IsAllocationHibernatedForSurfaceYes(stub4.allocation_));
+  EXPECT_TRUE(IsAllocationBackgroundForSurfaceNo(stub5.allocation_));
+  EXPECT_TRUE(IsAllocationHibernatedForSurfaceNo(stub6.allocation_));
+  EXPECT_TRUE(IsAllocationBackgroundForSurfaceNo(stub7.allocation_));
 }
 
 // Test GpuMemoryManager::Manage functionality: Test changing the last used
@@ -356,25 +390,25 @@ TEST_F(GpuMemoryManagerTest, TestManageChangingLastUsedTime) {
   client_.stubs_.push_back(&stub7);
 
   Manage();
-  EXPECT_EQ(stub3.allocation_.suggest_have_frontbuffer, true);
-  EXPECT_EQ(stub3.allocation_.suggest_have_backbuffer, false);
-  EXPECT_EQ(stub4.allocation_.suggest_have_frontbuffer, false);
-  EXPECT_EQ(stub4.allocation_.suggest_have_backbuffer, false);
-  EXPECT_EQ(stub5.allocation_, stub3.allocation_);
-  EXPECT_EQ(stub6.allocation_, stub4.allocation_);
-  EXPECT_EQ(stub7.allocation_, stub3.allocation_);
+  EXPECT_TRUE(IsAllocationBackgroundForSurfaceYes(stub1.allocation_));
+  EXPECT_TRUE(IsAllocationBackgroundForSurfaceYes(stub2.allocation_));
+  EXPECT_TRUE(IsAllocationBackgroundForSurfaceYes(stub3.allocation_));
+  EXPECT_TRUE(IsAllocationHibernatedForSurfaceYes(stub4.allocation_));
+  EXPECT_TRUE(IsAllocationBackgroundForSurfaceNo(stub5.allocation_));
+  EXPECT_TRUE(IsAllocationHibernatedForSurfaceNo(stub6.allocation_));
+  EXPECT_TRUE(IsAllocationBackgroundForSurfaceNo(stub7.allocation_));
 
   stub3.surface_state_.last_used_time = older_;
   stub4.surface_state_.last_used_time = newer_;
 
   Manage();
-  EXPECT_EQ(stub3.allocation_.suggest_have_frontbuffer, false);
-  EXPECT_EQ(stub3.allocation_.suggest_have_backbuffer, false);
-  EXPECT_EQ(stub4.allocation_.suggest_have_frontbuffer, true);
-  EXPECT_EQ(stub4.allocation_.suggest_have_backbuffer, false);
-  EXPECT_EQ(stub5.allocation_, stub3.allocation_);
-  EXPECT_EQ(stub6.allocation_, stub4.allocation_);
-  EXPECT_EQ(stub7.allocation_, stub4.allocation_);
+  EXPECT_TRUE(IsAllocationBackgroundForSurfaceYes(stub1.allocation_));
+  EXPECT_TRUE(IsAllocationBackgroundForSurfaceYes(stub2.allocation_));
+  EXPECT_TRUE(IsAllocationHibernatedForSurfaceYes(stub3.allocation_));
+  EXPECT_TRUE(IsAllocationBackgroundForSurfaceYes(stub4.allocation_));
+  EXPECT_TRUE(IsAllocationHibernatedForSurfaceNo(stub5.allocation_));
+  EXPECT_TRUE(IsAllocationBackgroundForSurfaceNo(stub6.allocation_));
+  EXPECT_TRUE(IsAllocationBackgroundForSurfaceNo(stub7.allocation_));
 }
 
 // Test GpuMemoryManager::Manage functionality: Test changing importance of
@@ -382,14 +416,14 @@ TEST_F(GpuMemoryManagerTest, TestManageChangingLastUsedTime) {
 // Expect memory allocation of the stubs without surface to share memory
 // allocation with the most visible stub in share group.
 TEST_F(GpuMemoryManagerTest, TestManageChangingImportanceShareGroup) {
-  FakeCommandBufferStub stubA(GenerateUniqueSurfaceId(), true, newer_),
-                        stubB(GenerateUniqueSurfaceId(), false, newer_),
-                        stubC(GenerateUniqueSurfaceId(), false, newer_);
+  FakeCommandBufferStub stubIgnoreA(GenerateUniqueSurfaceId(), true, newer_),
+                        stubIgnoreB(GenerateUniqueSurfaceId(), false, newer_),
+                        stubIgnoreC(GenerateUniqueSurfaceId(), false, newer_);
   FakeCommandBufferStub stub1(GenerateUniqueSurfaceId(), true, newest_),
                         stub2(GenerateUniqueSurfaceId(), true, newest_);
-  client_.stubs_.push_back(&stubA);
-  client_.stubs_.push_back(&stubB);
-  client_.stubs_.push_back(&stubC);
+  client_.stubs_.push_back(&stubIgnoreA);
+  client_.stubs_.push_back(&stubIgnoreB);
+  client_.stubs_.push_back(&stubIgnoreC);
   client_.stubs_.push_back(&stub1);
   client_.stubs_.push_back(&stub2);
 
@@ -402,62 +436,91 @@ TEST_F(GpuMemoryManagerTest, TestManageChangingImportanceShareGroup) {
   client_.stubs_.push_back(&stub4);
 
   Manage();
-  EXPECT_EQ(stub1.allocation_.suggest_have_frontbuffer, true);
-  EXPECT_EQ(stub1.allocation_.suggest_have_backbuffer, true);
-  EXPECT_EQ(stub2.allocation_.suggest_have_frontbuffer, true);
-  EXPECT_EQ(stub2.allocation_.suggest_have_backbuffer, true);
-  EXPECT_EQ(stub3.allocation_, stub1.allocation_);
-  EXPECT_EQ(stub3.allocation_, stub2.allocation_);
-  EXPECT_EQ(stub4.allocation_, stub1.allocation_);
-  EXPECT_EQ(stub4.allocation_, stub2.allocation_);
+  EXPECT_TRUE(IsAllocationForegroundForSurfaceYes(stub1.allocation_));
+  EXPECT_TRUE(IsAllocationForegroundForSurfaceYes(stub2.allocation_));
+  EXPECT_TRUE(IsAllocationForegroundForSurfaceNo(stub3.allocation_));
+  EXPECT_TRUE(IsAllocationForegroundForSurfaceNo(stub4.allocation_));
 
   stub1.surface_state_.visible = false;
 
   Manage();
-  EXPECT_EQ(stub1.allocation_.suggest_have_frontbuffer, true);
-  EXPECT_EQ(stub1.allocation_.suggest_have_backbuffer, false);
-  EXPECT_EQ(stub2.allocation_.suggest_have_frontbuffer, true);
-  EXPECT_EQ(stub2.allocation_.suggest_have_backbuffer, true);
-  EXPECT_NE(stub3.allocation_, stub1.allocation_);
-  EXPECT_EQ(stub3.allocation_, stub2.allocation_);
-  EXPECT_NE(stub4.allocation_, stub1.allocation_);
-  EXPECT_EQ(stub4.allocation_, stub2.allocation_);
+  EXPECT_TRUE(IsAllocationBackgroundForSurfaceYes(stub1.allocation_));
+  EXPECT_TRUE(IsAllocationForegroundForSurfaceYes(stub2.allocation_));
+  EXPECT_TRUE(IsAllocationBackgroundForSurfaceNo(stub3.allocation_));
+  EXPECT_TRUE(IsAllocationForegroundForSurfaceNo(stub4.allocation_));
 
   stub2.surface_state_.visible = false;
 
   Manage();
-  EXPECT_EQ(stub1.allocation_.suggest_have_frontbuffer, true);
-  EXPECT_EQ(stub1.allocation_.suggest_have_backbuffer, false);
-  EXPECT_EQ(stub2.allocation_.suggest_have_frontbuffer, true);
-  EXPECT_EQ(stub2.allocation_.suggest_have_backbuffer, false);
-  EXPECT_EQ(stub3.allocation_, stub1.allocation_);
-  EXPECT_EQ(stub3.allocation_, stub2.allocation_);
-  EXPECT_EQ(stub4.allocation_, stub1.allocation_);
-  EXPECT_EQ(stub4.allocation_, stub2.allocation_);
+  EXPECT_TRUE(IsAllocationBackgroundForSurfaceYes(stub1.allocation_));
+  EXPECT_TRUE(IsAllocationBackgroundForSurfaceYes(stub2.allocation_));
+  EXPECT_TRUE(IsAllocationBackgroundForSurfaceNo(stub3.allocation_));
+  EXPECT_TRUE(IsAllocationBackgroundForSurfaceNo(stub4.allocation_));
 
   stub1.surface_state_.last_used_time = older_;
 
   Manage();
-  EXPECT_EQ(stub1.allocation_.suggest_have_frontbuffer, false);
-  EXPECT_EQ(stub1.allocation_.suggest_have_backbuffer, false);
-  EXPECT_EQ(stub2.allocation_.suggest_have_frontbuffer, true);
-  EXPECT_EQ(stub2.allocation_.suggest_have_backbuffer, false);
-  EXPECT_NE(stub3.allocation_, stub1.allocation_);
-  EXPECT_EQ(stub3.allocation_, stub2.allocation_);
-  EXPECT_NE(stub4.allocation_, stub1.allocation_);
-  EXPECT_EQ(stub4.allocation_, stub2.allocation_);
+  EXPECT_TRUE(IsAllocationHibernatedForSurfaceYes(stub1.allocation_));
+  EXPECT_TRUE(IsAllocationBackgroundForSurfaceYes(stub2.allocation_));
+  EXPECT_TRUE(IsAllocationBackgroundForSurfaceNo(stub3.allocation_));
+  EXPECT_TRUE(IsAllocationBackgroundForSurfaceNo(stub4.allocation_));
 
   stub2.surface_state_.last_used_time = older_;
 
   Manage();
-  EXPECT_EQ(stub1.allocation_.suggest_have_frontbuffer, false);
-  EXPECT_EQ(stub1.allocation_.suggest_have_backbuffer, false);
-  EXPECT_EQ(stub2.allocation_.suggest_have_frontbuffer, false);
-  EXPECT_EQ(stub2.allocation_.suggest_have_backbuffer, false);
-  EXPECT_EQ(stub3.allocation_, stub1.allocation_);
-  EXPECT_EQ(stub3.allocation_, stub2.allocation_);
-  EXPECT_EQ(stub4.allocation_, stub1.allocation_);
-  EXPECT_EQ(stub4.allocation_, stub2.allocation_);
+  EXPECT_TRUE(IsAllocationHibernatedForSurfaceYes(stub1.allocation_));
+  EXPECT_TRUE(IsAllocationHibernatedForSurfaceYes(stub2.allocation_));
+  EXPECT_TRUE(IsAllocationHibernatedForSurfaceNo(stub3.allocation_));
+  EXPECT_TRUE(IsAllocationHibernatedForSurfaceNo(stub4.allocation_));
+}
+
+// Test GpuMemoryAllocation memory allocation bonuses:
+// When the number of visible tabs is small, each tab should get a
+// gpu_resource_size_in_bytes allocation value that is greater than
+// kMinimumAllocationForTab, and when the number of tabs is large, each should
+// get exactly kMinimumAllocationForTab and not less.
+TEST_F(GpuMemoryManagerTest, TestForegroundStubsGetBonusAllocation) {
+  FakeCommandBufferStub stub1(GenerateUniqueSurfaceId(), true, older_),
+                        stub2(GenerateUniqueSurfaceId(), true, older_),
+                        stub3(GenerateUniqueSurfaceId(), true, older_);
+  client_.stubs_.push_back(&stub1);
+  client_.stubs_.push_back(&stub2);
+  client_.stubs_.push_back(&stub3);
+
+  Manage();
+  EXPECT_TRUE(IsAllocationForegroundForSurfaceYes(stub1.allocation_));
+  EXPECT_TRUE(IsAllocationForegroundForSurfaceYes(stub2.allocation_));
+  EXPECT_TRUE(IsAllocationForegroundForSurfaceYes(stub3.allocation_));
+  EXPECT_GT(stub1.allocation_.gpu_resource_size_in_bytes,
+            static_cast<size_t>(GpuMemoryManager::kMinimumAllocationForTab));
+  EXPECT_GT(stub2.allocation_.gpu_resource_size_in_bytes,
+            static_cast<size_t>(GpuMemoryManager::kMinimumAllocationForTab));
+  EXPECT_GT(stub3.allocation_.gpu_resource_size_in_bytes,
+            static_cast<size_t>(GpuMemoryManager::kMinimumAllocationForTab));
+
+  FakeCommandBufferStub stub4(GenerateUniqueSurfaceId(), true, older_),
+                        stub5(GenerateUniqueSurfaceId(), true, older_),
+                        stub6(GenerateUniqueSurfaceId(), true, older_),
+                        stub7(GenerateUniqueSurfaceId(), true, older_),
+                        stub8(GenerateUniqueSurfaceId(), true, older_),
+                        stub9(GenerateUniqueSurfaceId(), true, older_);
+  client_.stubs_.push_back(&stub4);
+  client_.stubs_.push_back(&stub5);
+  client_.stubs_.push_back(&stub6);
+  client_.stubs_.push_back(&stub7);
+  client_.stubs_.push_back(&stub8);
+  client_.stubs_.push_back(&stub9);
+
+  Manage();
+  EXPECT_TRUE(IsAllocationForegroundForSurfaceYes(stub1.allocation_));
+  EXPECT_TRUE(IsAllocationForegroundForSurfaceYes(stub2.allocation_));
+  EXPECT_TRUE(IsAllocationForegroundForSurfaceYes(stub3.allocation_));
+  EXPECT_EQ(stub1.allocation_.gpu_resource_size_in_bytes,
+            GpuMemoryManager::kMinimumAllocationForTab);
+  EXPECT_EQ(stub2.allocation_.gpu_resource_size_in_bytes,
+            GpuMemoryManager::kMinimumAllocationForTab);
+  EXPECT_EQ(stub3.allocation_.gpu_resource_size_in_bytes,
+            GpuMemoryManager::kMinimumAllocationForTab);
 }
 
 // Test GpuMemoryAllocation comparison operators: Iterate over all possible
@@ -465,21 +528,35 @@ TEST_F(GpuMemoryManagerTest, TestManageChangingImportanceShareGroup) {
 // suggest_have_frontbuffer, and make sure allocations with equal values test
 // equal and non equal values test not equal.
 TEST_F(GpuMemoryManagerTest, GpuMemoryAllocationCompareTests) {
-  int gpu_resource_size_in_bytes_values[] = { 0, 1, 12345678 };
-  bool suggest_have_backbuffer_values[] = { false, true };
-  bool suggest_have_frontbuffer_values[] = { false, true };
-
-  for(int* sz = &gpu_resource_size_in_bytes_values[0];
-      sz != &gpu_resource_size_in_bytes_values[3]; ++sz) {
-    for(bool* shbb = &suggest_have_backbuffer_values[0];
-        shbb != &suggest_have_backbuffer_values[2]; ++shbb) {
-      for(bool* shfb = &suggest_have_frontbuffer_values[0];
-          shfb != &suggest_have_frontbuffer_values[2]; ++shfb) {
-        GpuMemoryAllocation allocation(*sz, *shbb, *shfb);
-        EXPECT_EQ(allocation, GpuMemoryAllocation(*sz, *shbb, *shfb));
-        EXPECT_NE(allocation, GpuMemoryAllocation(*sz+1, *shbb, *shfb));
-        EXPECT_NE(allocation, GpuMemoryAllocation(*sz, !*shbb, *shfb));
-        EXPECT_NE(allocation, GpuMemoryAllocation(*sz, *shbb, !*shfb));
+  std::vector<int> gpu_resource_size_in_bytes_values;
+  gpu_resource_size_in_bytes_values.push_back(0);
+  gpu_resource_size_in_bytes_values.push_back(1);
+  gpu_resource_size_in_bytes_values.push_back(12345678);
+
+  std::vector<int> suggested_buffer_allocation_values;
+  suggested_buffer_allocation_values.push_back(
+      GpuMemoryAllocation::kHasFrontbuffer |
+      GpuMemoryAllocation::kHasBackbuffer);
+  suggested_buffer_allocation_values.push_back(
+      GpuMemoryAllocation::kHasFrontbuffer);
+  suggested_buffer_allocation_values.push_back(
+      GpuMemoryAllocation::kHasBackbuffer);
+  suggested_buffer_allocation_values.push_back(
+      GpuMemoryAllocation::kHasNoBuffers);
+
+  for(size_t i = 0; i != gpu_resource_size_in_bytes_values.size(); ++i) {
+    for(size_t j = 0; j != suggested_buffer_allocation_values.size(); ++j) {
+      int sz = gpu_resource_size_in_bytes_values[i];
+      int buffer_allocation = suggested_buffer_allocation_values[j];
+      GpuMemoryAllocation allocation(sz, buffer_allocation);
+
+      EXPECT_EQ(allocation, GpuMemoryAllocation(sz, buffer_allocation));
+      EXPECT_NE(allocation, GpuMemoryAllocation(sz+1, buffer_allocation));
+
+      for(size_t k = 0; k != suggested_buffer_allocation_values.size(); ++k) {
+        int buffer_allocation_other = suggested_buffer_allocation_values[k];
+        if (buffer_allocation == buffer_allocation_other) continue;
+        EXPECT_NE(allocation, GpuMemoryAllocation(sz, buffer_allocation_other));
       }
     }
   }
diff --git a/content/common/gpu/gpu_messages.h b/content/common/gpu/gpu_messages.h
index d76491a..d921b3b 100644
--- a/content/common/gpu/gpu_messages.h
+++ b/content/common/gpu/gpu_messages.h
@@ -445,6 +445,11 @@ IPC_MESSAGE_ROUTED0(GpuCommandBufferMsg_EnsureBackbuffer)
 IPC_MESSAGE_ROUTED1(GpuCommandBufferMsg_SetMemoryAllocation,
                     GpuMemoryAllocationForRenderer /* allocation */)
 
+// Sent to stub when proxy is assigned a memory allocation changed callback.
+IPC_MESSAGE_ROUTED1(
+    GpuCommandBufferMsg_SetClientHasMemoryAllocationChangedCallback,
+    bool /* has_callback */)
+
 //------------------------------------------------------------------------------
 // Accelerated Video Decoder Messages
 // These messages are sent from Renderer process to GPU process.