Drop frontbuffers with ui-use-gpu-process, synchronized with browser, decoupled from backbuffer dro…

content/common/gpu/gpu_command_buffer_stub.cc

Index: content/common/gpu/gpu_command_buffer_stub.cc
diff --git a/content/common/gpu/gpu_command_buffer_stub.cc b/content/common/gpu/gpu_command_buffer_stub.cc
index 41fa5e5a2ffd6158f1b6e13370cc69f961b1f879..1085040a1cf1e09017ffda29a7aba7229caa899e 100644
--- a/content/common/gpu/gpu_command_buffer_stub.cc
+++ b/content/common/gpu/gpu_command_buffer_stub.cc
@@ -59,9 +59,6 @@ GpuCommandBufferStub::GpuCommandBufferStub(
       route_id_(route_id),
       software_(software),
       last_flush_count_(0),
-      allocation_(GpuMemoryAllocation::INVALID_RESOURCE_SIZE,
-                  GpuMemoryAllocation::kHasFrontbuffer |
-                  GpuMemoryAllocation::kHasBackbuffer),
       parent_stub_for_initialization_(),
       parent_texture_for_initialization_(0),
       watchdog_(watchdog) {
@@ -578,20 +575,13 @@ void GpuCommandBufferStub::OnSetSurfaceVisible(bool visible) {
 void GpuCommandBufferStub::OnDiscardBackbuffer() {
   if (!surface_)
     return;
-  if (allocation_.suggest_have_frontbuffer)
-    surface_->SetBufferAllocation(
-        gfx::GLSurface::BUFFER_ALLOCATION_FRONT_ONLY);
-  else
-    surface_->SetBufferAllocation(
-        gfx::GLSurface::BUFFER_ALLOCATION_NONE);
+  surface_->SetBackbufferAllocation(false);
 }
 
 void GpuCommandBufferStub::OnEnsureBackbuffer() {
   if (!surface_)
     return;
-  // TODO(mmocny): Support backbuffer without frontbuffer.
-  surface_->SetBufferAllocation(
-      gfx::GLSurface::BUFFER_ALLOCATION_FRONT_AND_BACK);
+  surface_->SetBackbufferAllocation(true);
 }
 
 void GpuCommandBufferStub::OnSetClientHasMemoryAllocationChangedCallback(
@@ -643,16 +633,12 @@ const GpuCommandBufferStubBase::SurfaceState&
   return *surface_state_.get();
 }
 
-void GpuCommandBufferStub::SendMemoryAllocationToProxy(
-    const GpuMemoryAllocation& allocation) {
-  Send(new GpuCommandBufferMsg_SetMemoryAllocation(route_id_, allocation));
-}
-
 void GpuCommandBufferStub::SetMemoryAllocation(
     const GpuMemoryAllocation& allocation) {
-  allocation_ = allocation;
-
-  SendMemoryAllocationToProxy(allocation);
+  Send(new GpuCommandBufferMsg_SetMemoryAllocation(route_id_, allocation));
+  if (!surface_)
+    return;
+  surface_->SetFrontbufferAllocation(allocation.suggest_have_frontbuffer);
 }
 
 #endif  // defined(ENABLE_GPU)