Query the preferred readback config in CopyFromBackingStore

content/browser/renderer_host/render_widget_host_view_android.cc

Index: content/browser/renderer_host/render_widget_host_view_android.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_android.cc b/content/browser/renderer_host/render_widget_host_view_android.cc
index fdc7810375eb907c8fe2b6decebddd50447fc996..10dbfeb6c4bfa960f9d738fb55d85d0dade1b953 100644
--- a/content/browser/renderer_host/render_widget_host_view_android.cc
+++ b/content/browser/renderer_host/render_widget_host_view_android.cc
@@ -6,6 +6,7 @@
 
 #include <android/bitmap.h>
 
+#include "base/android/sys_utils.h"
 #include "base/basictypes.h"
 #include "base/bind.h"
 #include "base/callback_helpers.h"
@@ -1386,6 +1387,17 @@ bool RenderWidgetHostViewAndroid::IsReadbackConfigSupported(
   return gl_helper->IsReadbackConfigSupported(bitmap_config);
 }
 
+SkBitmap::Config RenderWidgetHostViewAndroid::PreferredReadbackFormat() {
+  // Define the criteria here. If say the 16 texture readback is
+  // supported we should go with that (this degrades quality)
+  // or stick back to the default format.
+  if (base::android::SysUtils::IsLowEndDevice()) {
+    if (IsReadbackConfigSupported(SkBitmap::kRGB_565_Config))
+      return SkBitmap::kRGB_565_Config;
+  }
+  return SkBitmap::kARGB_8888_Config;
+}
+
 // static
 void RenderWidgetHostViewPort::GetDefaultScreenInfo(
     blink::WebScreenInfo* results) {