Adds a TransportDIB::Id value that is explicitly invalid and use it when compositing

BUG=76001
TEST=

Review URL: http://codereview.chromium.org/6665029

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@79349 0039d316-1c4b-4281-b951-d872f2087c98

5 files changed, 46 insertions, 19 deletions

diff --git a/app/surface/accelerated_surface_mac.cc b/app/surface/accelerated_surface_mac.cc
index ab5529e..6322603 100644
--- a/app/surface/accelerated_surface_mac.cc
+++ b/app/surface/accelerated_surface_mac.cc
@@ -307,7 +307,7 @@ TransportDIB::Handle AcceleratedSurface::SetTransportDIBSize(
   if (dib_alloc_callback_.get()) {
     dib_alloc_callback_->Run(dib_size, &dib_handle);
   }
-  if (!TransportDIB::is_valid(dib_handle)) {
+  if (!TransportDIB::is_valid_handle(dib_handle)) {
     // If the allocator fails, it means the DIB was not created in the browser,
     // so there is no need to run the deallocator here.
     return TransportDIB::DefaultHandleValue();
diff --git a/app/surface/transport_dib.h b/app/surface/transport_dib.h
index a55f624..d13168a 100644
--- a/app/surface/transport_dib.h
+++ b/app/surface/transport_dib.h
@@ -56,7 +56,7 @@ class TransportDIB {
           sequence_num(seq_num) {
     }
 
-    bool operator< (const HandleAndSequenceNum& other) const {
+    bool operator<(const HandleAndSequenceNum& other) const {
       // Use the lexicographic order on the tuple <handle, sequence_num>.
       if (other.handle != handle)
         return other.handle < handle;
@@ -95,7 +95,17 @@ class TransportDIB {
   }
 #elif defined(USE_X11)
   typedef int Handle;  // These two ints are SysV IPC shared memory keys
-  typedef int Id;
+  struct Id {
+    // Ensure that default initialized Ids are invalid.
+    Id() : shmkey(-1) {
+    }
+
+    bool operator<(const Id& other) const {
+      return shmkey < other.shmkey;
+    }
+
+    int shmkey;
+  };
 
   // Returns a default, invalid handle, that is meant to indicate a missing
   // Transport DIB.
@@ -129,7 +139,10 @@ class TransportDIB {
   static TransportDIB* CreateWithHandle(Handle handle);
 
   // Returns true if the handle is valid.
-  static bool is_valid(Handle dib);
+  static bool is_valid_handle(Handle dib);
+
+  // Returns true if the ID refers to a valid dib.
+  static bool is_valid_id(Id id);
 
   // Returns a canvas using the memory of this TransportDIB. The returned
   // pointer will be owned by the caller. The bitmap will be of the given size,
@@ -176,7 +189,7 @@ class TransportDIB {
   base::SharedMemory shared_memory_;
   uint32 sequence_num_;
 #elif defined(USE_X11)
-  int key_;  // SysV shared memory id
+  Id key_;  // SysV shared memory id
   void* address_;  // mapped address
   XSharedMemoryId x_shm_;  // X id for the shared segment
   Display* display_;  // connection to the X server
diff --git a/app/surface/transport_dib_linux.cc b/app/surface/transport_dib_linux.cc
index 69fabff..614cdb0 100644
--- a/app/surface/transport_dib_linux.cc
+++ b/app/surface/transport_dib_linux.cc
@@ -18,8 +18,7 @@
 static void *const kInvalidAddress = (void*) -1;
 
 TransportDIB::TransportDIB()
-    : key_(-1),
-      address_(kInvalidAddress),
+    : address_(kInvalidAddress),
       x_shm_(0),
       display_(NULL),
       size_(0) {
@@ -59,7 +58,7 @@ TransportDIB* TransportDIB::Create(size_t size, uint32 sequence_num) {
 
   TransportDIB* dib = new TransportDIB;
 
-  dib->key_ = shmkey;
+  dib->key_.shmkey = shmkey;
   dib->address_ = address;
   dib->size_ = size;
   return dib;
@@ -76,15 +75,20 @@ TransportDIB* TransportDIB::Map(Handle handle) {
 // static
 TransportDIB* TransportDIB::CreateWithHandle(Handle shmkey) {
   TransportDIB* dib = new TransportDIB;
-  dib->key_ = shmkey;
+  dib->key_.shmkey = shmkey;
   return dib;
 }
 
 // static
-bool TransportDIB::is_valid(Handle dib) {
+bool TransportDIB::is_valid_handle(Handle dib) {
   return dib >= 0;
 }
 
+// static
+bool TransportDIB::is_valid_id(Id id) {
+  return id.shmkey != -1;
+}
+
 skia::PlatformCanvas* TransportDIB::GetPlatformCanvas(int w, int h) {
   if (address_ == kInvalidAddress && !Map())
     return NULL;
@@ -95,16 +99,16 @@ skia::PlatformCanvas* TransportDIB::GetPlatformCanvas(int w, int h) {
 }
 
 bool TransportDIB::Map() {
-  if (!is_valid(key_))
+  if (!is_valid_id(key_))
     return false;
   if (address_ != kInvalidAddress)
     return true;
 
   struct shmid_ds shmst;
-  if (shmctl(key_, IPC_STAT, &shmst) == -1)
+  if (shmctl(key_.shmkey, IPC_STAT, &shmst) == -1)
     return false;
 
-  void* address = shmat(key_, NULL /* desired address */, 0 /* flags */);
+  void* address = shmat(key_.shmkey, NULL /* desired address */, 0 /* flags */);
   if (address == kInvalidAddress)
     return false;
 
@@ -123,12 +127,12 @@ TransportDIB::Id TransportDIB::id() const {
 }
 
 TransportDIB::Handle TransportDIB::handle() const {
-  return key_;
+  return key_.shmkey;
 }
 
 XID TransportDIB::MapToX(Display* display) {
   if (!x_shm_) {
-    x_shm_ = ui::AttachSharedMemory(display, key_);
+    x_shm_ = ui::AttachSharedMemory(display, key_.shmkey);
     display_ = display;
   }
 
diff --git a/app/surface/transport_dib_mac.cc b/app/surface/transport_dib_mac.cc
index 8ea81ae..c0dd457 100644
--- a/app/surface/transport_dib_mac.cc
+++ b/app/surface/transport_dib_mac.cc
@@ -51,10 +51,15 @@ TransportDIB* TransportDIB::CreateWithHandle(Handle handle) {
 }
 
 // static
-bool TransportDIB::is_valid(Handle dib) {
+bool TransportDIB::is_valid_handle(Handle dib) {
   return dib.fd >= 0;
 }
 
+// static
+bool TransportDIB::is_valid_id(Id id) {
+  return id != 0;
+}
+
 skia::PlatformCanvas* TransportDIB::GetPlatformCanvas(int w, int h) {
   if (!memory() && !Map())
     return NULL;
@@ -65,7 +70,7 @@ skia::PlatformCanvas* TransportDIB::GetPlatformCanvas(int w, int h) {
 }
 
 bool TransportDIB::Map() {
-  if (!is_valid(handle()))
+  if (!is_valid_handle(handle()))
     return false;
   if (memory())
     return true;
diff --git a/app/surface/transport_dib_win.cc b/app/surface/transport_dib_win.cc
index 22812c9..3de7fab 100644
--- a/app/surface/transport_dib_win.cc
+++ b/app/surface/transport_dib_win.cc
@@ -56,10 +56,15 @@ TransportDIB* TransportDIB::CreateWithHandle(Handle handle) {
 }
 
 // static
-bool TransportDIB::is_valid(Handle dib) {
+bool TransportDIB::is_valid_handle(Handle dib) {
   return dib != NULL;
 }
 
+// static
+bool TransportDIB::is_valid_id(TransportDIB::Id id) {
+  return is_valid_handle(id.handle);
+}
+
 skia::PlatformCanvas* TransportDIB::GetPlatformCanvas(int w, int h) {
   // This DIB already mapped the file into this process, but PlatformCanvas
   // will map it again.
@@ -72,7 +77,7 @@ skia::PlatformCanvas* TransportDIB::GetPlatformCanvas(int w, int h) {
 }
 
 bool TransportDIB::Map() {
-  if (!is_valid(handle()))
+  if (!is_valid_handle(handle()))
     return false;
   if (memory())
     return true;