android webview: allow cc to fail hardware draw

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 "cc/output/compositor_frame.h"
 #include "cc/output/context_provider.h"
@@ skipping 58 matching lines @@
           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),
       frame_swap_message_queue_(frame_swap_message_queue) {
   thread_checker_.DetachFromThread();
   DCHECK(registry_);
-  capabilities_.draw_and_swap_full_viewport_every_frame = true;
   capabilities_.adjust_deadline_for_parent = false;
   capabilities_.delegated_rendering = true;
   capabilities_.max_frames_pending = 1;
   memory_policy_.priority_cutoff_when_visible =
       gpu::MemoryAllocation::CUTOFF_ALLOW_NICE_TO_HAVE;
 }
 
 SynchronousCompositorOutputSurface::~SynchronousCompositorOutputSurface() {}
 
 void SynchronousCompositorOutputSurface::SetSyncClient(
@@ skipping 98 matching lines @@
     gfx::Rect viewport_rect_for_tile_priority,
     gfx::Transform transform_for_tile_priority,
     bool hardware_draw) {
   DCHECK(!frame_holder_.get());
 
   gfx::Transform adjusted_transform = transform;
   adjusted_transform.matrix().postTranslate(-viewport.x(), -viewport.y(), 0);
   SetExternalDrawConstraints(adjusted_transform, viewport, clip,
                              viewport_rect_for_tile_priority,
                              transform_for_tile_priority, !hardware_draw);
-  SetNeedsRedrawRect(gfx::Rect(viewport.size()));
+  if (!hardware_draw) {
+    SetNeedsRedrawRect(gfx::Rect(viewport.size()));

[brianderson, 2015/10/22 20:53:35]

Does this also need to be called for the first hardware draw after a software
draw? Or alternatively accumulate the damage rects of all previous software
draws and union that with the damage for the first hardware draw?

[boliu, 2015/10/22 20:57:53]

Good question. I think the answer is yes.

This is proably better: move all this damage logic into LTHI::OnDraw as well.
Then for software, save the damage at the beginning, damage viewport, draw, and
restore the old damage. That would be the "right" behavior I think?

[boliu, 2015/10/22 21:50:08]

Keeping it at the end of InvokeComposite here for now.

+  }
 
   client_->OnDraw();
 
   // After software draws (which might move the viewport arbitrarily), restore
   // the previous hardware viewport to allow CC's tile manager to prioritize
   // properly.
   if (hardware_draw) {
     cached_hw_transform_ = adjusted_transform;
     cached_hw_viewport_ = viewport;
     cached_hw_clip_ = clip;
@@ skipping 53 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