OnDrawHardware() implementation with async messages

android_webview/browser/browser_view_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/browser_view_renderer.h"
 
 #include <utility>
 
 #include "android_webview/browser/browser_view_renderer_client.h"
 #include "android_webview/browser/child_frame.h"
@@ skipping 218 matching lines @@
   // If the WebView is on a layer, WebView does not know what transform is
   // applied onto the layer so global visible rect does not make sense here.
   // In this case, just use the surface rect for tiling.
   gfx::Rect viewport_rect_for_tile_priority;
 
   // Leave viewport_rect_for_tile_priority empty if offscreen_pre_raster_ is on.
   if (!offscreen_pre_raster_ && !external_draw_constraints_.is_layer) {
     viewport_rect_for_tile_priority = last_on_draw_global_visible_rect_;
   }
 
+  // If AFLAG true, will use semi-asynchronous implementation.
+  bool AFLAG = false;

[boliu, 2016/08/11 19:23:39]

Here is an example of an actual command line switch, although the CL is for
removing it

https://codereview.chromium.org/1913723002

basically you add a string to android_webview/common/aw_switches.cc/h, then
check for it using base::CommandLine::ForCurrentProcess

only check once though, not every frame

[ojars, 2016/08/17 22:51:33]

Done.

+  if (AFLAG) {
+    compositor_->DemandDrawHw_Async(size_, viewport_rect_for_tile_priority,
+                                    transform_for_tile_priority);
+
+    return current_compositor_frame_consumer_->HasFrameOnUI();
+  }
+
   content::SynchronousCompositor::Frame frame = compositor_->DemandDrawHw(
       size_, viewport_rect_for_tile_priority, transform_for_tile_priority);
   if (!frame.frame.get()) {
     TRACE_EVENT_INSTANT0("android_webview", "NoNewFrame",
                          TRACE_EVENT_SCOPE_THREAD);
     return current_compositor_frame_consumer_->HasFrameOnUI();
   }
 
   std::unique_ptr<ChildFrame> child_frame = base::WrapUnique(new ChildFrame(
       frame.output_surface_id, std::move(frame.frame), compositor_id_,
       viewport_rect_for_tile_priority.IsEmpty(), transform_for_tile_priority,
       offscreen_pre_raster_, external_draw_constraints_.is_layer));
 
   ReturnUnusedResource(
       current_compositor_frame_consumer_->PassUncommittedFrameOnUI());
   current_compositor_frame_consumer_->SetFrameOnUI(std::move(child_frame));
   return true;
 }
 
+void BrowserViewRenderer::OnDrawHardwareProcessFrame(
+    content::SynchronousCompositor::Frame frame) {
+  TRACE_EVENT0("android_webview",
+               "BrowserViewRenderer::OnDrawHardwareProcessFrame");
+
+  if (!frame.frame.get())
+    return;
+
+  gfx::Transform transform_for_tile_priority =
+      external_draw_constraints_.transform;
+
+  // If the WebView is on a layer, WebView does not know what transform is
+  // applied onto the layer so global visible rect does not make sense here.
+  // In this case, just use the surface rect for tiling.
+  gfx::Rect viewport_rect_for_tile_priority;
+
+  // Leave viewport_rect_for_tile_priority empty if offscreen_pre_raster_ is on.
+  if (!offscreen_pre_raster_ && !external_draw_constraints_.is_layer) {
+    viewport_rect_for_tile_priority = last_on_draw_global_visible_rect_;
+  }
+
+  std::unique_ptr<ChildFrame> child_frame = base::WrapUnique(new ChildFrame(
+      frame.output_surface_id, std::move(frame.frame), compositor_id_,
+      viewport_rect_for_tile_priority.IsEmpty(), transform_for_tile_priority,
+      offscreen_pre_raster_, external_draw_constraints_.is_layer));
+
+  ReturnUnusedResource(
+      current_compositor_frame_consumer_->PassUncommittedFrameOnUI());
+  current_compositor_frame_consumer_->SetFrameOnUI(std::move(child_frame));
+}
+
 void BrowserViewRenderer::OnParentDrawConstraintsUpdated(
     CompositorFrameConsumer* compositor_frame_consumer) {
   DCHECK(compositor_frame_consumer);
   if (compositor_frame_consumer != current_compositor_frame_consumer_)
     return;
   PostInvalidate(compositor_);
   external_draw_constraints_ =
       current_compositor_frame_consumer_->GetParentDrawConstraintsOnUI();
   UpdateMemoryPolicy();
 }
@@ skipping 464 matching lines @@
   base::StringAppendF(&str,
                       "overscroll_rounding_error_: %s ",
                       overscroll_rounding_error_.ToString().c_str());
   base::StringAppendF(
       &str, "on_new_picture_enable: %d ", on_new_picture_enable_);
   base::StringAppendF(&str, "clear_view: %d ", clear_view_);
   return str;
 }
 
 }  // namespace android_webview