Android Webview IPC-based sync compositing

content/renderer/gpu/render_widget_compositor.cc

 // Copyright (c) 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/gpu/render_widget_compositor.h"
 
 #include <limits>
 #include <string>
 
 #include "base/command_line.h"
@@ skipping 354 matching lines @@
         cc::switches::kSlowDownRasterScaleFactor,
         kMinSlowDownScaleFactor,
         kMaxSlowDownScaleFactor,
         &settings.initial_debug_state.slow_down_raster_scale_factor);
   }
 
   settings.strict_layer_property_change_checking =
       cmd->HasSwitch(cc::switches::kStrictLayerPropertyChangeChecking);
 
 #if defined(OS_ANDROID)
-  SynchronousCompositorFactory* synchronous_compositor_factory =
-      SynchronousCompositorFactory::GetInstance();
+  DCHECK(!SynchronousCompositorFactory::GetInstance() ||
+         !cmd->HasSwitch(switches::kIPCSyncCompositing));
+  bool using_synchronous_compositor =
+      SynchronousCompositorFactory::GetInstance() ||
+      cmd->HasSwitch(switches::kIPCSyncCompositing);
 
   // We can't use GPU rasterization on low-end devices, because the Ganesh
   // cache would consume too much memory.
   if (base::SysInfo::IsLowEndDevice())
     settings.gpu_rasterization_enabled = false;
-  settings.using_synchronous_renderer_compositor =
-      synchronous_compositor_factory;
+  settings.using_synchronous_renderer_compositor = using_synchronous_compositor;
   settings.record_full_layer = widget_->DoesRecordFullLayer();
-  if (synchronous_compositor_factory) {
+  if (using_synchronous_compositor) {
     // Android WebView uses system scrollbars, so make ours invisible.
     settings.scrollbar_animator = cc::LayerTreeSettings::NO_ANIMATOR;
     settings.solid_color_scrollbar_color = SK_ColorTRANSPARENT;
   } else {
     settings.scrollbar_animator = cc::LayerTreeSettings::LINEAR_FADE;
     settings.scrollbar_fade_delay_ms = 300;
     settings.scrollbar_fade_resize_delay_ms = 2000;
     settings.scrollbar_fade_duration_ms = 300;
     settings.solid_color_scrollbar_color = SkColorSetARGB(128, 128, 128, 128);
   }
   settings.renderer_settings.highp_threshold_min = 2048;
   // Android WebView handles root layer flings itself.
-  settings.ignore_root_layer_flings =
-      synchronous_compositor_factory;
+  settings.ignore_root_layer_flings = using_synchronous_compositor;
   // Memory policy on Android WebView does not depend on whether device is
   // low end, so always use default policy.
   bool use_low_memory_policy =
-      base::SysInfo::IsLowEndDevice() && !synchronous_compositor_factory;
+      base::SysInfo::IsLowEndDevice() && !using_synchronous_compositor;
   // RGBA_4444 textures are only enabled by default for low end devices
   // and are disabled for Android WebView as it doesn't support the format.
   settings.renderer_settings.use_rgba_4444_textures = use_low_memory_policy;
   if (use_low_memory_policy) {
     // On low-end we want to be very carefull about killing other
     // apps. So initially we use 50% more memory to avoid flickering
     // or raster-on-demand.
     settings.max_memory_for_prepaint_percentage = 67;
   } else {
     // On other devices we have increased memory excessively to avoid
     // raster-on-demand already, so now we reserve 50% _only_ to avoid
     // raster-on-demand, and use 50% of the memory otherwise.
     settings.max_memory_for_prepaint_percentage = 50;
   }
   // Webview does not own the surface so should not clear it.
   settings.renderer_settings.should_clear_root_render_pass =
-      !synchronous_compositor_factory;
+      !using_synchronous_compositor;
 
   // TODO(danakj): Only do this on low end devices.
   settings.create_low_res_tiling = true;
 
   settings.use_external_begin_frame_source = true;
 
 #elif !defined(OS_MACOSX)
   if (ui::IsOverlayScrollbarEnabled()) {
     settings.scrollbar_animator = cc::LayerTreeSettings::THINNING;
     settings.solid_color_scrollbar_color = SkColorSetARGB(128, 128, 128, 128);
@@ skipping 650 matching lines @@
 #endif
   return actual;
 }
 
 void RenderWidgetCompositor::SetPaintedDeviceScaleFactor(
     float device_scale) {
   layer_tree_host_->SetPaintedDeviceScaleFactor(device_scale);
 }
 
 }  // namespace content