aw: Use minimum_accelerated_2d_canvas_size to turn canvas on/off

android_webview/native/aw_settings.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 "android_webview/native/aw_settings.h"
 
 #include "android_webview/browser/renderer_host/aw_render_view_host_ext.h"
 #include "android_webview/common/aw_content_client.h"
 #include "android_webview/native/aw_contents.h"
 #include "base/android/jni_android.h"
@@ skipping 308 matching lines @@
   web_prefs->viewport_meta_zero_values_quirk = support_quirks;
   web_prefs->clobber_user_agent_initial_scale_quirk = support_quirks;
   web_prefs->ignore_main_frame_overflow_hidden_quirk = support_quirks;
   web_prefs->report_screen_size_in_physical_pixels_quirk = support_quirks;
 
   web_prefs->password_echo_enabled =
       Java_AwSettings_getPasswordEchoEnabledLocked(env, obj);
   web_prefs->spatial_navigation_enabled =
       Java_AwSettings_getSpatialNavigationLocked(env, obj);
 
-  web_prefs->accelerated_2d_canvas_enabled =
-      !accelerated_2d_canvas_disabled_by_switch_ &&
-      Java_AwSettings_getEnableSupportedHardwareAcceleratedFeaturesLocked(
-          env, obj);
+  web_prefs->accelerated_2d_canvas_enabled = true;
+  if (accelerated_2d_canvas_disabled_by_switch_ ||
+      !Java_AwSettings_getEnableSupportedHardwareAcceleratedFeaturesLocked(
+          env, obj)) {
+    // Any canvas smaller than this will fallback to software. Abusing this
+    // slightly to turn canvas off without changing
+    // accelerated_2d_canvas_enabled, which also affects compositing mode.
+    web_prefs->minimum_accelerated_2d_canvas_size =
+        std::numeric_limits<int>::max();

[aelias_OOO_until_Jul13, 2014/03/25 23:58:16]

INT_MAX is prone to strange bugs because you cannot add or multiply it.  Please
go with 100 million instead.

+  }
 }
 
 static jlong Init(JNIEnv* env,
                   jobject obj,
                   jlong web_contents) {
   AwSettings* settings = new AwSettings(env, obj, web_contents);
   return reinterpret_cast<intptr_t>(settings);
 }
 
 static jstring GetDefaultUserAgent(JNIEnv* env, jclass clazz) {
   return base::android::ConvertUTF8ToJavaString(env, GetUserAgent()).Release();
 }
 
 bool RegisterAwSettings(JNIEnv* env) {
   return RegisterNativesImpl(env) >= 0;
 }
 
 }  // namespace android_webview