aw: Fallback delegated composite

android_webview/browser/hardware_renderer.cc

 // Copyright 2014 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 "android_webview/browser/hardware_renderer.h"
 
 #include "android_webview/browser/aw_gl_surface.h"
 #include "android_webview/browser/deferred_gpu_command_service.h"
 #include "android_webview/browser/parent_output_surface.h"
 #include "android_webview/browser/shared_renderer_state.h"
@@ skipping 122 matching lines @@
   // This is called after OutputSurface is created, but before the impl frame
   // starts. We set the draw constraints here.
   DCHECK(output_surface_);
   DCHECK(viewport_clip_valid_for_dcheck_);
   output_surface_->SetExternalStencilTest(stencil_enabled_);
   output_surface_->SetDrawConstraints(viewport_, clip_);
 }
 
 void HardwareRenderer::CommitFrame() {
   scroll_offset_ = shared_renderer_state_->GetScrollOffset();
-  if (committed_frame_.get()) {
+  if (committed_frame_.get() && !shared_renderer_state_->ForceCommit()) {
     TRACE_EVENT_INSTANT0("android_webview",
                          "EarlyOut_PreviousFrameUnconsumed",
                          TRACE_EVENT_SCOPE_THREAD);
     return;
   }
 
   committed_frame_ = shared_renderer_state_->PassCompositorFrame();

[hush (inactive), 2014/10/15 18:17:30]

since ForceCommmit() stays true until the next onDraw produces a frame to
SharedRendererState, commitFrame() could be called multiple times before
DrawGL() right? So committed_frame_ produced by the fallback tick may not be
consumed by DrawGL.

[boliu, 2014/10/15 19:37:51]

As discussed, fixed. Just don't have the new condition as it's not needed.

   // Happens with empty global visible rect.
   if (!committed_frame_.get())
     return;
 
   DCHECK(!committed_frame_->gl_frame_data);
   DCHECK(!committed_frame_->software_frame_data);
 
   // DelegatedRendererLayerImpl applies the inverse device_scale_factor of the
   // renderer frame, assuming that the browser compositor will scale
   // it back up to device scale.  But on Android we put our browser layers in
@@ skipping 38 matching lines @@
   // We need to watch if the current Android context has changed and enforce
   // a clean-up in the compositor.
   EGLContext current_context = eglGetCurrentContext();
   DCHECK(current_context) << "DrawGL called without EGLContext";
 
   // TODO(boliu): Handle context loss.
   if (last_egl_context_ != current_context)
     DLOG(WARNING) << "EGLContextChanged";
 
   SetFrameData();
+  if (shared_renderer_state_->ForceCommit()) {
+    CommitFrame();
+    SetFrameData();

[boliu, 2014/10/15 18:01:25]

Hmm, my guess is it doesn't like having 2 frames shoved into the layer at once??
That would really suck and make this more complicated...

[hush (inactive), 2014/10/15 18:17:30]

you committed frame data twice. I don't know what that does.
Supposedly your fallback tick's frame data is most recent, and you can just drop
the previous frames' data.

+  }
+
   gfx::Transform transform(gfx::Transform::kSkipInitialization);
   transform.matrix().setColMajorf(draw_info->transform);
   transform.Translate(scroll_offset_.x(), scroll_offset_.y());
 
   // Need to post the new transform matrix back to child compositor
   // because there is no onDraw during a Render Thread animation, and child
   // compositor might not have the tiles rasterized as the animation goes on.
   ParentCompositorDrawConstraints draw_constraints(
       draw_info->is_layer, transform, gfx::Rect(viewport_));
 
@@ skipping 38 matching lines @@
 }
 
 void HardwareRenderer::UnusedResourcesAreAvailable() {
   cc::ReturnedResourceArray returned_resources;
   resource_collection_->TakeUnusedResourcesForChildCompositor(
       &returned_resources);
   shared_renderer_state_->InsertReturnedResources(returned_resources);
 }
 
 }  // namespace android_webview