Support for '--force-compositing-mode', see WebKit bug 56156

BUG=
TEST=


Review URL: http://codereview.chromium.org/6665057

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@78904 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 9 insertions, 0 deletions

diff --git a/chrome/browser/tab_contents/render_view_host_delegate_helper.cc b/chrome/browser/tab_contents/render_view_host_delegate_helper.cc
index f5d686b..f88dddb 100644
--- a/chrome/browser/tab_contents/render_view_host_delegate_helper.cc
+++ b/chrome/browser/tab_contents/render_view_host_delegate_helper.cc
@@ -293,6 +293,8 @@ WebPreferences RenderViewHostDelegateHelper::GetWebkitPrefs(
     web_prefs.accelerated_compositing_enabled =
         gpu_enabled() &&
         !command_line.HasSwitch(switches::kDisableAcceleratedCompositing);
+    web_prefs.force_compositing_mode =
+        command_line.HasSwitch(switches::kForceCompositingMode);
     web_prefs.accelerated_2d_canvas_enabled =
         gpu_enabled() &&
         command_line.HasSwitch(switches::kEnableAccelerated2dCanvas);
diff --git a/chrome/common/chrome_switches.cc b/chrome/common/chrome_switches.cc
index 01e4d6a..7286e94 100644
--- a/chrome/common/chrome_switches.cc
+++ b/chrome/common/chrome_switches.cc
@@ -611,6 +611,10 @@ const char kFirstRun[]                      = "first-run";
 // timed out, etc. Useful for testing.
 const char kForceAppsPromoVisible[]         = "force-apps-promo-visible";
 
+// If accelerated compositing is supported, always enter compositing mode for
+// the base layer even when compositing is not strictly required.
+const char kForceCompositingMode[]          = "force-compositing-mode";
+
 // Some field tests may rendomized in the browser, and the randomly selected
 // outcome needs to be propogated to the renderer.  For instance, this is used
 // to modify histograms recorded in the renderer, or to get the renderer to
diff --git a/chrome/common/chrome_switches.h b/chrome/common/chrome_switches.h
index e7bc4da..7550cff 100644
--- a/chrome/common/chrome_switches.h
+++ b/chrome/common/chrome_switches.h
@@ -182,6 +182,7 @@ extern const char kFileDescriptorLimit[];
 extern const char kFocusExistingTabOnOpen[];
 extern const char kFirstRun[];
 extern const char kForceAppsPromoVisible[];
+extern const char kForceCompositingMode[];
 extern const char kForceFieldTestNameAndValue[];
 extern const char kForceRendererAccessibility[];
 extern const char kForceStubLibcros[];
diff --git a/chrome/common/render_messages.cc b/chrome/common/render_messages.cc
index c05d761..52d7280 100644
--- a/chrome/common/render_messages.cc
+++ b/chrome/common/render_messages.cc
@@ -410,6 +410,7 @@ void ParamTraits<WebPreferences>::Write(Message* m, const param_type& p) {
   WriteParam(m, p.show_composited_layer_tree);
   WriteParam(m, p.show_fps_counter);
   WriteParam(m, p.accelerated_compositing_enabled);
+  WriteParam(m, p.force_compositing_mode);
   WriteParam(m, p.composite_to_texture_enabled);
   WriteParam(m, p.accelerated_2d_canvas_enabled);
   WriteParam(m, p.accelerated_plugins_enabled);
@@ -470,6 +471,7 @@ bool ParamTraits<WebPreferences>::Read(const Message* m, void** iter,
       ReadParam(m, iter, &p->show_composited_layer_tree) &&
       ReadParam(m, iter, &p->show_fps_counter) &&
       ReadParam(m, iter, &p->accelerated_compositing_enabled) &&
+      ReadParam(m, iter, &p->force_compositing_mode) &&
       ReadParam(m, iter, &p->composite_to_texture_enabled) &&
       ReadParam(m, iter, &p->accelerated_2d_canvas_enabled) &&
       ReadParam(m, iter, &p->accelerated_plugins_enabled) &&