Decoupling backbuffer allocation suggestion from frontbuffer allocation suggestion.

content/common/gpu/texture_image_transport_surface.cc

Index: content/common/gpu/texture_image_transport_surface.cc
diff --git a/content/common/gpu/texture_image_transport_surface.cc b/content/common/gpu/texture_image_transport_surface.cc
index de9d3357c228ed844581e5710786f2b608f67197..bd40acf892203dcee9b17303ad931950e1b12595 100644
--- a/content/common/gpu/texture_image_transport_surface.cc
+++ b/content/common/gpu/texture_image_transport_surface.cc
@@ -65,6 +65,8 @@ TextureImageTransportSurface::TextureImageTransportSurface(
       : fbo_id_(0),
         front_(0),
         stub_destroyed_(false),
+        backbuffer_suggested_allocation_(true),
+        frontbuffer_suggested_allocation_(true),
         parent_stub_(NULL) {
   GpuChannel* parent_channel = manager->LookupChannel(handle.parent_client_id);
   DCHECK(parent_channel);
@@ -155,19 +157,27 @@ unsigned int TextureImageTransportSurface::GetBackingFrameBufferObject() {
   return fbo_id_;
 }
 
-void TextureImageTransportSurface::SetBufferAllocation(
-    BufferAllocationState state) {
+void TextureImageTransportSurface::SetBackbufferAllocation(bool allocation) {
+  if (backbuffer_suggested_allocation_ == allocation)
+     return;
+  backbuffer_suggested_allocation_ = allocation;
+  AdjustBufferAllocations();
+}
+
+void TextureImageTransportSurface::SetFrontbufferAllocation(bool allocation) {
+  if (frontbuffer_suggested_allocation_ == allocation)
+    return;
+  frontbuffer_suggested_allocation_ = allocation;
+  AdjustBufferAllocations();

[jonathan.backer, 2012/05/09 18:13:01]

Why are we doing this when AdjustBufferAllocations ignores it?

[mmocny, 2012/05/09 18:59:15]

Just for consistency.  I can remove it from this patch and add it once it does
something.

On 2012/05/09 18:13:01, jonathan.backer wrote:

[jonathan.backer, 2012/05/10 21:37:48]

I'm concerned that order of allocating buffers matters. For example, when a tab
is made visible, we may allocate a front and back buffer when previously we had
none. If we allocate the back and then the front, we will call CreateBackTexture
twice in AdjustBufferAllocations.

+}
+
+void TextureImageTransportSurface::AdjustBufferAllocations() {
   if (!helper_->MakeCurrent())
     return;
-  switch (state) {
-    case BUFFER_ALLOCATION_FRONT_AND_BACK:
-      CreateBackTexture(textures_[back()].size);
-      break;
-    case BUFFER_ALLOCATION_FRONT_ONLY:
-    case BUFFER_ALLOCATION_NONE:
-      ReleaseBackTexture();
-      break;
-  };
+  if (backbuffer_suggested_allocation_)
+    CreateBackTexture(textures_[back()].size);
+  else
+    ReleaseBackTexture();
 }
 
 void* TextureImageTransportSurface::GetShareHandle() {