GPU: Only allow the UI channel to preempt if all stubs are scheduled.

content/common/gpu/gpu_command_buffer_stub.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "base/hash.h"
 #include "base/shared_memory.h"
@@ skipping 252 matching lines @@
 void GpuCommandBufferStub::OnEcho(const IPC::Message& message) {
   TRACE_EVENT0("gpu", "GpuCommandBufferStub::OnEcho");
   Send(new IPC::Message(message));
 }
 
 void GpuCommandBufferStub::OnReschedule() {
   if (!IsScheduled())
     return;
 
   channel_->OnScheduled();
+  channel_->StubSchedulingChanged();
 }
 
 bool GpuCommandBufferStub::MakeCurrent() {
   if (decoder_->MakeCurrent())
     return true;
   DLOG(ERROR) << "Context lost because MakeCurrent failed.";
   command_buffer_->SetContextLostReason(decoder_->GetContextLostReason());
   command_buffer_->SetParseError(gpu::error::kLostContext);
   if (gfx::GLContext::LosesAllContextsOnContextLost())
     channel_->LoseAllContexts();
@@ skipping 197 matching lines @@
 
   command_buffer_->SetPutOffsetChangeCallback(
       base::Bind(&GpuCommandBufferStub::PutChanged, base::Unretained(this)));
   command_buffer_->SetGetBufferChangeCallback(
       base::Bind(&gpu::GpuScheduler::SetGetBuffer,
                  base::Unretained(scheduler_.get())));
   command_buffer_->SetParseErrorCallback(
       base::Bind(&GpuCommandBufferStub::OnParseError, base::Unretained(this)));
   scheduler_->SetScheduledCallback(
       base::Bind(&GpuCommandBufferStub::OnReschedule, base::Unretained(this)));
+  scheduler_->SetDescheduledCallback(
+      base::Bind(&GpuChannel::StubSchedulingChanged,
+                 base::Unretained(channel_)));

[piman, 2013/02/27 21:54:43]

Could we merge the 2 callbacks (eg passing the scheduled flag, or having the
callback check IsScheduled() )?
It's easier to follow if both paths get routed to the same class, and it avoids
the explosion of callbacks.

[jonathan.backer, 2013/02/28 21:43:56]

Done.

 
   if (watchdog_) {
     scheduler_->SetCommandProcessedCallback(
         base::Bind(&GpuCommandBufferStub::OnCommandProcessed,
                    base::Unretained(this)));
   }
 
 #if defined(OS_ANDROID)
   decoder_->SetStreamTextureManager(channel_->stream_texture_manager());
 #endif
@@ skipping 379 matching lines @@
     if (surface_ && MakeCurrent())
       surface_->SetFrontbufferAllocation(
           allocation.browser_allocation.suggest_have_frontbuffer);
   }
 
   last_memory_allocation_valid_ = true;
   last_memory_allocation_ = allocation;
 }
 
 }  // namespace content