Move fallback tick handling to compositor thread

content/renderer/android/synchronous_compositor_output_surface.cc

 // Copyright 2013 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 "content/renderer/android/synchronous_compositor_output_surface.h"
 
 #include "base/auto_reset.h"
 #include "base/logging.h"
 #include "base/macros.h"
 #include "cc/output/compositor_frame.h"
 #include "cc/output/context_provider.h"
 #include "cc/output/output_surface_client.h"
 #include "cc/output/software_output_device.h"
 #include "content/renderer/android/synchronous_compositor_external_begin_frame_source.h"
 #include "content/renderer/android/synchronous_compositor_registry.h"
 #include "content/renderer/gpu/frame_swap_message_queue.h"
 #include "gpu/command_buffer/client/context_support.h"
 #include "gpu/command_buffer/client/gles2_interface.h"
 #include "gpu/command_buffer/common/gpu_memory_allocation.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 #include "ui/gfx/geometry/rect_conversions.h"
 #include "ui/gfx/skia_util.h"
 #include "ui/gfx/transform.h"
 
 namespace content {
 
 namespace {
 
+const int64_t kFallbackTickTimeoutInMilliseconds = 100;
+
 // Do not limit number of resources, so use an unrealistically high value.
 const size_t kNumResourcesLimit = 10 * 1000 * 1000;
 
 }  // namespace
 
 class SynchronousCompositorOutputSurface::SoftwareDevice
   : public cc::SoftwareOutputDevice {
  public:
   SoftwareDevice(SynchronousCompositorOutputSurface* surface)
     : surface_(surface) {
@@ skipping 29 matching lines @@
           context_provider,
           worker_context_provider,
           scoped_ptr<cc::SoftwareOutputDevice>(new SoftwareDevice(this))),
       routing_id_(routing_id),
       registry_(registry),
       registered_(false),
       sync_client_(nullptr),
       current_sw_canvas_(nullptr),
       memory_policy_(0u),
       did_swap_(false),
-      frame_swap_message_queue_(frame_swap_message_queue) {
+      frame_swap_message_queue_(frame_swap_message_queue),
+      fallback_tick_pending_(false),
+      fallback_tick_running_(false) {
   thread_checker_.DetachFromThread();
   DCHECK(registry_);
   capabilities_.adjust_deadline_for_parent = false;
   capabilities_.delegated_rendering = true;
   memory_policy_.priority_cutoff_when_visible =
       gpu::MemoryAllocation::CUTOFF_ALLOW_NICE_TO_HAVE;
 }
 
 SynchronousCompositorOutputSurface::~SynchronousCompositorOutputSurface() {}
 
@@ skipping 31 matching lines @@
 void SynchronousCompositorOutputSurface::Reshape(const gfx::Size& size,
                                                  float scale_factor,
                                                  bool has_alpha) {
   // Intentional no-op: surface size is controlled by the embedder.
 }
 
 void SynchronousCompositorOutputSurface::SwapBuffers(
     cc::CompositorFrame* frame) {
   DCHECK(CalledOnValidThread());
   DCHECK(sync_client_);
-  sync_client_->SwapBuffers(frame);
+  if (!fallback_tick_running_) sync_client_->SwapBuffers(frame);

[boliu, 2016/03/15 15:10:54]

c++ style says this is should be on two lines

[Tobias Sargeant, 2016/03/16 17:29:27]

Huh. I thought so, but clang-format didn't reindent it, so I assumed that it
wasn't gospel. But then git cl format did. I'll check my clang-format config.

[in fact clang-format'ing the line actively puts it back like this]

   client_->DidSwapBuffers();
   did_swap_ = true;
 }
 
+void SynchronousCompositorOutputSurface::FallbackTickFired() {
+  DCHECK(CalledOnValidThread());
+  TRACE_EVENT0("renderer",
+               "SynchronousCompositorOutputSurface::FallbackTickFired");
+  base::AutoReset<bool> in_fallback_tick(&fallback_tick_running_, true);
+  SkBitmap bitmap;
+  bitmap.allocN32Pixels(1, 1);
+  bitmap.eraseColor(0);
+  SkCanvas canvas(bitmap);
+  DemandDrawSw(&canvas);
+  fallback_tick_pending_ = false;

[boliu, 2016/03/15 15:10:54]

subtle: but should do this before DemandDrawSw, in case DemandDrawSw calls
invalidate internally.

[Tobias Sargeant, 2016/03/16 17:29:27]

Done.

+}
+
 void SynchronousCompositorOutputSurface::Invalidate() {
   DCHECK(CalledOnValidThread());
   if (sync_client_)
     sync_client_->Invalidate();
+
+  if (!fallback_tick_pending_) {
+    fallback_tick_.Reset(
+        base::Bind(&SynchronousCompositorOutputSurface::FallbackTickFired,
+                   base::Unretained(this)));
+    base::MessageLoop::current()->PostDelayedTask(
+        FROM_HERE, fallback_tick_.callback(),
+        base::TimeDelta::FromMilliseconds(kFallbackTickTimeoutInMilliseconds));
+    fallback_tick_pending_ = true;
+  }
 }
 
 void SynchronousCompositorOutputSurface::DemandDrawHw(
     const gfx::Size& surface_size,
     const gfx::Transform& transform,
     const gfx::Rect& viewport,
     const gfx::Rect& clip,
     const gfx::Rect& viewport_rect_for_tile_priority,
     const gfx::Transform& transform_for_tile_priority) {
   DCHECK(CalledOnValidThread());
   DCHECK(HasClient());
   DCHECK(context_provider_.get());
+  fallback_tick_.Cancel();
+  fallback_tick_pending_ = false;
 
   surface_size_ = surface_size;
   client_->SetExternalTilePriorityConstraints(viewport_rect_for_tile_priority,
                                               transform_for_tile_priority);
   const bool software_draw = false;
   InvokeComposite(transform, viewport, clip, software_draw);
 }
 
 void SynchronousCompositorOutputSurface::DemandDrawSw(SkCanvas* canvas) {
   DCHECK(CalledOnValidThread());
   DCHECK(canvas);
   DCHECK(!current_sw_canvas_);
+  fallback_tick_.Cancel();
+  fallback_tick_pending_ = false;
 
   base::AutoReset<SkCanvas*> canvas_resetter(&current_sw_canvas_, canvas);
 
   SkIRect canvas_clip;
   canvas->getClipDeviceBounds(&canvas_clip);
   gfx::Rect clip = gfx::SkIRectToRect(canvas_clip);
 
   gfx::Transform transform(gfx::Transform::kSkipInitialization);
   transform.matrix() = canvas->getTotalMatrix();  // Converts 3x3 matrix to 4x4.
 
@@ skipping 56 matching lines @@
   scoped_ptr<FrameSwapMessageQueue::SendMessageScope> send_message_scope =
       frame_swap_message_queue_->AcquireSendMessageScope();
   frame_swap_message_queue_->DrainMessages(messages);
 }
 
 bool SynchronousCompositorOutputSurface::CalledOnValidThread() const {
   return thread_checker_.CalledOnValidThread();
 }
 
 }  // namespace content