Plumb thru that we cache the front buffer.

This allows us to drop the root layer textures and save on VRAM (10 MB on a 30" display).

WebKit side patch: https://bugs.webkit.org/show_bug.cgi?id=72956

BUG=none
TEST='cat /proc/meminfo | grep Shmem' on Intel graphics and use_aura=1 attached to 30" display

Review URL: http://codereview.chromium.org/8637014

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@111532 0039d316-1c4b-4281-b951-d872f2087c98

5 files changed, 68 insertions, 12 deletions

diff --git a/content/common/gpu/image_transport_surface_linux.cc b/content/common/gpu/image_transport_surface_linux.cc
index e106a9f..10ceae2 100644
--- a/content/common/gpu/image_transport_surface_linux.cc
+++ b/content/common/gpu/image_transport_surface_linux.cc
@@ -62,7 +62,7 @@ class EGLImageTransportSurface : public ImageTransportSurface,
                            int32 renderer_id,
                            int32 command_buffer_id);
 
-  // GLSurface implementation
+  // gfx::GLSurface implementation
   virtual bool Initialize() OVERRIDE;
   virtual void Destroy() OVERRIDE;
   virtual bool IsOffscreen() OVERRIDE;
@@ -115,6 +115,7 @@ class GLXImageTransportSurface : public ImageTransportSurface,
   virtual void Destroy() OVERRIDE;
   virtual bool SwapBuffers() OVERRIDE;
   virtual bool PostSubBuffer(int x, int y, int width, int height) OVERRIDE;
+  virtual std::string GetExtensions();
   virtual gfx::Size GetSize() OVERRIDE;
   virtual bool OnMakeCurrent(gfx::GLContext* context) OVERRIDE;
   virtual void SetVisible(bool visible) OVERRIDE;
@@ -254,7 +255,7 @@ EGLImageTransportSurface::~EGLImageTransportSurface() {
 bool EGLImageTransportSurface::Initialize() {
   if (!helper_->Initialize())
     return false;
-  return PbufferGLSurfaceEGL::Initialize();
+  return gfx::PbufferGLSurfaceEGL::Initialize();
 }
 
 void EGLImageTransportSurface::Destroy() {
@@ -264,7 +265,7 @@ void EGLImageTransportSurface::Destroy() {
     ReleaseSurface(&front_surface_);
 
   helper_->Destroy();
-  PbufferGLSurfaceEGL::Destroy();
+  gfx::PbufferGLSurfaceEGL::Destroy();
 }
 
 // Make sure that buffer swaps occur for the surface, so we can send the data
@@ -378,7 +379,10 @@ bool EGLImageTransportSurface::PostSubBuffer(
 }
 
 std::string EGLImageTransportSurface::GetExtensions() {
-  return GLSurface::GetExtensions();
+  std::string extensions = gfx::GLSurface::GetExtensions();
+  extensions += extensions.empty() ? "" : " ";
+  extensions += "GL_CHROMIUM_front_buffer_cached";
+  return extensions;
 }
 
 gfx::Size EGLImageTransportSurface::GetSize() {
@@ -562,6 +566,13 @@ bool GLXImageTransportSurface::PostSubBuffer(
   return true;
 }
 
+std::string GLXImageTransportSurface::GetExtensions() {
+  std::string extensions = gfx::NativeViewGLSurfaceGLX::GetExtensions();
+  extensions += extensions.empty() ? "" : " ";
+  extensions += "GL_CHROMIUM_front_buffer_cached";
+  return extensions;
+}
+
 gfx::Size GLXImageTransportSurface::GetSize() {
   return size_;
 }
@@ -708,7 +719,10 @@ bool OSMesaImageTransportSurface::PostSubBuffer(
 }
 
 std::string OSMesaImageTransportSurface::GetExtensions() {
-  return GLSurface::GetExtensions();
+  std::string extensions = gfx::GLSurface::GetExtensions();
+  extensions += extensions.empty() ? "" : " ";
+  extensions += "GL_CHROMIUM_front_buffer_cached";
+  return extensions;
 }
 
 void OSMesaImageTransportSurface::OnBuffersSwappedACK() {
diff --git a/content/common/gpu/image_transport_surface_mac.cc b/content/common/gpu/image_transport_surface_mac.cc
index b7d9676..91af588 100644
--- a/content/common/gpu/image_transport_surface_mac.cc
+++ b/content/common/gpu/image_transport_surface_mac.cc
@@ -89,6 +89,7 @@ class TransportDIBImageTransportSurface : public gfx::PbufferGLSurfaceCGL,
   virtual void Destroy() OVERRIDE;
   virtual bool IsOffscreen() OVERRIDE;
   virtual bool SwapBuffers() OVERRIDE;
+  virtual bool PostSubBuffer(int x, int y, int width, int height) OVERRIDE;
   virtual std::string GetExtensions() OVERRIDE;
   virtual gfx::Size GetSize() OVERRIDE;
   virtual bool OnMakeCurrent(gfx::GLContext* context) OVERRIDE;
@@ -238,7 +239,10 @@ bool IOSurfaceImageTransportSurface::PostSubBuffer(
 }
 
 std::string IOSurfaceImageTransportSurface::GetExtensions() {
-  return gfx::GLSurface::GetExtensions();
+  std::string extensions = gfx::GLSurface::GetExtensions();
+  extensions += extensions.empty() ? "" : " ";
+  extensions += "GL_CHROMIUM_front_buffer_cached";
+  return extensions;
 }
 
 gfx::Size IOSurfaceImageTransportSurface::GetSize() {
@@ -451,8 +455,17 @@ bool TransportDIBImageTransportSurface::SwapBuffers() {
   return true;
 }
 
+bool TransportDIBImageTransportSurface::PostSubBuffer(
+    int x, int y, int width, int height) {
+  NOTREACHED();
+  return false;
+}
+
 std::string TransportDIBImageTransportSurface::GetExtensions() {
-  return gfx::GLSurface::GetExtensions();
+  std::string extensions = gfx::GLSurface::GetExtensions();
+  extensions += extensions.empty() ? "" : " ";
+  extensions += "GL_CHROMIUM_front_buffer_cached";
+  return extensions;
 }
 
 gfx::Size TransportDIBImageTransportSurface::GetSize() {
diff --git a/content/common/gpu/image_transport_surface_win.cc b/content/common/gpu/image_transport_surface_win.cc
index f3eb9d5a..a33c466 100644
--- a/content/common/gpu/image_transport_surface_win.cc
+++ b/content/common/gpu/image_transport_surface_win.cc
@@ -32,11 +32,13 @@ class PbufferImageTransportSurface
                                int32 renderer_id,
                                int32 command_buffer_id);
 
-  // GLSurface implementation
-  virtual bool Initialize();
-  virtual void Destroy();
-  virtual bool IsOffscreen();
-  virtual bool SwapBuffers();
+  // gfx::GLSurface implementation
+  virtual bool Initialize() OVERRIDE;
+  virtual void Destroy() OVERRIDE;
+  virtual bool IsOffscreen() OVERRIDE;
+  virtual bool SwapBuffers() OVERRIDE;
+  virtual bool PostSubBuffer(int x, int y, int width, int height) OVERRIDE;
+  virtual std::string GetExtensions() OVERRIDE;
 
  protected:
   // ImageTransportSurface implementation
@@ -109,6 +111,19 @@ bool PbufferImageTransportSurface::SwapBuffers() {
   return true;
 }
 
+bool PbufferImageTransportSurface::PostSubBuffer(
+    int x, int y, int width, int height) {
+  NOTREACHED();
+  return false;
+}
+
+std::string PbufferImageTransportSurface::GetExtensions() {
+  std::string extensions = gfx::GLSurface::GetExtensions();
+  extensions += extensions.empty() ? "" : " ";
+  extensions += "GL_CHROMIUM_front_buffer_cached";
+  return extensions;
+}
+
 void PbufferImageTransportSurface::SendBuffersSwapped() {
   GpuHostMsg_AcceleratedSurfaceBuffersSwapped_Params params;
   params.surface_id = reinterpret_cast<int64>(GetShareHandle());
diff --git a/gpu/command_buffer/service/feature_info.cc b/gpu/command_buffer/service/feature_info.cc
index 66c05a8..ea74412 100644
--- a/gpu/command_buffer/service/feature_info.cc
+++ b/gpu/command_buffer/service/feature_info.cc
@@ -393,6 +393,10 @@ void FeatureInfo::AddFeatures(const char* desired_features) {
   if (ext.HaveAndDesire("GL_CHROMIUM_post_sub_buffer")) {
     AddExtensionString("GL_CHROMIUM_post_sub_buffer");
   }
+
+  if (ext.HaveAndDesire("GL_CHROMIUM_front_buffer_cached")) {
+    AddExtensionString("GL_CHROMIUM_front_buffer_cached");
+  }
 }
 
 void FeatureInfo::AddExtensionString(const std::string& str) {
diff --git a/third_party/khronos/GLES2/gl2ext.h b/third_party/khronos/GLES2/gl2ext.h
index 4ddf729..f1a49dc 100644
--- a/third_party/khronos/GLES2/gl2ext.h
+++ b/third_party/khronos/GLES2/gl2ext.h
@@ -1366,6 +1366,16 @@ typedef void (GL_APIENTRYP PFNGLPOSTSUBBUFFERCHROMIUM) (GLint x, GLint y, GLint
 #endif
 #endif
 
+/* GL_CHROMIUM_front_buffer_cached */
+/* This extension implies that there is a cache of the front buffer of the
+ * surface supporting this extension (e.g. on OSX the front buffer
+ * is often backed by an IOSurface). Hence we do not need to redraw
+ * (via a SwapBuffers) in order to display the last frame.
+ */
+#ifndef GL_CHROMIUM_front_buffer_cached
+#define GL_CHROMIUM_front_buffer_cached 1
+#endif
+
 /* GL_ARB_robustness */
 /* This extension is subsetted for the moment, incorporating only the
  * enums necessary to describe the reasons that we might encounter for