GPU: Adjust memory and use the soft-limit.

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>
 
 #if defined(OS_ANDROID)
@@ skipping 244 matching lines @@
   settings.highp_threshold_min = 2048;
   // Android WebView handles root layer flings itself.
   settings.ignore_root_layer_flings =
       widget->UsingSynchronousRendererCompositor();
   // RGBA_4444 textures are only enabled for low end devices
   // and are disabled for Android WebView as it doesn't support the format.
   settings.use_rgba_4444_textures =
       base::android::SysUtils::IsLowEndDevice() &&
       !widget->UsingSynchronousRendererCompositor() &&
       !cmd->HasSwitch(cc::switches::kDisable4444Textures);
+  if (widget->UsingSynchronousRendererCompositor()) {
+    // TODO(boliu): Set this ratio for Webview.
+  } else if (base::android::SysUtils::IsLowEndDevice()) {
+    // On low-end we want to be very carefull about killing other
+    // apps. So initially we use 50% more memory to avoid flickering

[klobag.chromium, 2014/02/15 07:27:20]

comment 50% is not matching code 67%.

[epenner, 2014/02/17 05:43:23]

Oh, yes this comment is very confusing. We do actually use 50% more (12MB vs
8MB), so this is 8/12 = 67%.  I'll clean this up to be more clear.

+    // 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;
+  }
+
 #elif !defined(OS_MACOSX)
   if (IsOverlayScrollbarEnabled()) {
     settings.scrollbar_animator = cc::LayerTreeSettings::Thinning;
     settings.solid_color_scrollbar_color = SkColorSetARGB(128, 128, 128, 128);
   } else if (cmd->HasSwitch(cc::switches::kEnablePinchVirtualViewport)) {
     settings.scrollbar_animator = cc::LayerTreeSettings::LinearFade;
     settings.solid_color_scrollbar_color = SkColorSetARGB(128, 128, 128, 128);
   }
 #endif
 
@@ skipping 350 matching lines @@
   widget_->OnSwapBuffersAborted();
 }
 
 void RenderWidgetCompositor::RateLimitSharedMainThreadContext() {
   cc::ContextProvider* provider =
       RenderThreadImpl::current()->SharedMainThreadContextProvider().get();
   provider->ContextGL()->RateLimitOffscreenContextCHROMIUM();
 }
 
 }  // namespace content