Revert "Revert "Enable composited iframes on hi-DPI.""

This was a speculative revert. It turned out not to be the problem. Relanding.

This reverts commit 9797adb04362cd267e9727c506deebade23446d8.

TBR=zeeshan@chromium.org
BUG=306566

Review URL: https://codereview.chromium.org/27709003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@229126 0039d316-1c4b-4281-b951-d872f2087c98

7 files changed, 96 insertions, 4 deletions

diff --git a/chrome/app/generated_resources.grd b/chrome/app/generated_resources.grd
index 7aa78be..fa8918f 100644
--- a/chrome/app/generated_resources.grd
+++ b/chrome/app/generated_resources.grd
@@ -6785,6 +6785,18 @@ Keep your key file in a safe place. You will need it to create new versions of y
       <message name="IDS_FLAGS_HIDPI_DESCRIPTION" desc="Description of flag to enable/disable HiDPI Support.">
         If enabled, application size and layout will adapt to the operating system's DPI settings.
       </message>
+      <message name="IDS_FLAGS_ENABLE_ACCELERATED_SCROLLABLE_FRAMES_NAME" desc="Name of the flag to enable accelerated scrollable frames.">
+        Enable accelerated scrollable frames.
+      </message>
+      <message name="IDS_FLAGS_ENABLE_ACCELERATED_SCROLLABLE_FRAMES_DESCRIPTION" desc="Description for the flag to enable accelerated scrollable frames.">
+        Enables accelerated compositing for scrollable frames.
+      </message>
+      <message name="IDS_FLAGS_ENABLE_COMPOSITED_SCROLLING_FOR_FRAMES_NAME" desc="Name of the flag to enable composited scrolling for frames.">
+        Enable composited scrolling for frames.
+      </message>
+      <message name="IDS_FLAGS_ENABLE_COMPOSITED_SCROLLING_FOR_FRAMES_DESCRIPTION" desc="Description for the flag to enable composited scrolling for frames.">
+        Enable accelerated scrolling by the compositer for frames.
+      </message>
       <message name="IDS_FLAGS_ENABLE_STREAMLINED_HOSTED_APPS_NAME" desc="Name of the flag to enable streamlined hosted apps.">
         Enable experimental streamlined hosted apps.
       </message>
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index ec224ae..66ec1c7 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -1751,6 +1751,22 @@ const Experiment kExperiments[] = {
     SINGLE_VALUE_TYPE(cc::switches::kDisableCompositorTouchHitTesting),
   },
   {
+    "enable-accelerated-scrollable-frames",
+     IDS_FLAGS_ENABLE_ACCELERATED_SCROLLABLE_FRAMES_NAME,
+     IDS_FLAGS_ENABLE_ACCELERATED_SCROLLABLE_FRAMES_DESCRIPTION,
+     kOsAll,
+     ENABLE_DISABLE_VALUE_TYPE(switches::kEnableAcceleratedScrollableFrames,
+                               switches::kDisableAcceleratedScrollableFrames)
+  },
+  {
+    "enable-composited-scrolling-for-frames",
+     IDS_FLAGS_ENABLE_COMPOSITED_SCROLLING_FOR_FRAMES_NAME,
+     IDS_FLAGS_ENABLE_COMPOSITED_SCROLLING_FOR_FRAMES_DESCRIPTION,
+     kOsAll,
+     ENABLE_DISABLE_VALUE_TYPE(switches::kEnableCompositedScrollingForFrames,
+                               switches::kDisableCompositedScrollingForFrames)
+  },
+  {
     "enable-streamlined-hosted-apps",
     IDS_FLAGS_ENABLE_STREAMLINED_HOSTED_APPS_NAME,
     IDS_FLAGS_ENABLE_STREAMLINED_HOSTED_APPS_DESCRIPTION,
diff --git a/content/browser/renderer_host/render_process_host_impl.cc b/content/browser/renderer_host/render_process_host_impl.cc
index 177533c..5336df8 100644
--- a/content/browser/renderer_host/render_process_host_impl.cc
+++ b/content/browser/renderer_host/render_process_host_impl.cc
@@ -872,10 +872,12 @@ void RenderProcessHostImpl::PropagateBrowserCommandLineToRenderer(
     switches::kDisable3DAPIs,
     switches::kDisableAcceleratedCompositing,
     switches::kDisableAcceleratedFixedRootBackground,
+    switches::kDisableAcceleratedScrollableFrames,
     switches::kDisableAcceleratedVideoDecode,
     switches::kDisableApplicationCache,
     switches::kDisableAudio,
     switches::kDisableBreakpad,
+    switches::kDisableCompositedScrollingForFrames,
     switches::kDisableCompositingForFixedPosition,
     switches::kDisableCompositingForTransition,
     switches::kDisableDatabases,
@@ -911,9 +913,11 @@ void RenderProcessHostImpl::PropagateBrowserCommandLineToRenderer(
     switches::kDomAutomationController,
     switches::kEnableAcceleratedFixedRootBackground,
     switches::kEnableAcceleratedOverflowScroll,
+    switches::kEnableAcceleratedScrollableFrames,
     switches::kEnableAccessibilityLogging,
     switches::kEnableBeginFrameScheduling,
     switches::kEnableBrowserPluginForAllViewTypes,
+    switches::kEnableCompositedScrollingForFrames,
     switches::kEnableCompositingForFixedPosition,
     switches::kEnableCompositingForTransition,
     switches::kEnableDCHECK,
diff --git a/content/browser/web_contents/web_contents_impl.cc b/content/browser/web_contents/web_contents_impl.cc
index 7f68273..64a91f4 100644
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -521,10 +521,18 @@ WebPreferences WebContentsImpl::GetWebkitPrefs(RenderViewHost* rvh,
   if (command_line.HasSwitch(switches::kDisableAcceleratedOverflowScroll))
     prefs.accelerated_compositing_for_overflow_scroll_enabled = false;
 
-  prefs.accelerated_compositing_for_scrollable_frames_enabled =
-      command_line.HasSwitch(switches::kEnableAcceleratedScrollableFrames);
-  prefs.composited_scrolling_for_frames_enabled =
-      command_line.HasSwitch(switches::kEnableCompositedScrollingForFrames);
+  prefs.accelerated_compositing_for_scrollable_frames_enabled = false;
+  if (command_line.HasSwitch(switches::kEnableAcceleratedScrollableFrames))
+    prefs.accelerated_compositing_for_scrollable_frames_enabled = true;
+  if (command_line.HasSwitch(switches::kDisableAcceleratedScrollableFrames))
+    prefs.accelerated_compositing_for_scrollable_frames_enabled = false;
+
+  prefs.composited_scrolling_for_frames_enabled = false;
+  if (command_line.HasSwitch(switches::kEnableCompositedScrollingForFrames))
+    prefs.composited_scrolling_for_frames_enabled = true;
+  if (command_line.HasSwitch(switches::kDisableCompositedScrollingForFrames))
+    prefs.composited_scrolling_for_frames_enabled = false;
+
   prefs.show_paint_rects =
       command_line.HasSwitch(switches::kShowPaintRects);
   prefs.accelerated_compositing_enabled =
diff --git a/content/public/common/content_switches.cc b/content/public/common/content_switches.cc
index 0167733..158c4f9 100644
--- a/content/public/common/content_switches.cc
+++ b/content/public/common/content_switches.cc
@@ -90,6 +90,10 @@ const char kDisableAcceleratedLayers[]      = "disable-accelerated-layers";
 const char kDisableAcceleratedOverflowScroll[] =
     "disable-accelerated-overflow-scroll";
 
+// Disable accelerated compositing for scrollable frames.
+const char kDisableAcceleratedScrollableFrames[] =
+     "disable-accelerated-scrollable-frames";
+
 // Disables the hardware acceleration of plugins.
 const char kDisableAcceleratedPlugins[]     = "disable-accelerated-plugins";
 
@@ -118,6 +122,10 @@ const char kDisableBackingStoreLimit[]      = "disable-backing-store-limit";
 const char kDisableBrowserPluginCompositing[] =
     "disable-browser-plugin-compositing";
 
+// Disable accelerated scrolling by the compositor for frames.
+const char kDisableCompositedScrollingForFrames[] =
+     "disable-composited-scrolling-for-frames";
+
 // See comment for kEnableCompositingForFixedPosition.
 const char kDisableCompositingForFixedPosition[] =
      "disable-fixed-position-compositing";
diff --git a/content/public/common/content_switches.h b/content/public/common/content_switches.h
index c895113..6ecdd25 100644
--- a/content/public/common/content_switches.h
+++ b/content/public/common/content_switches.h
@@ -38,6 +38,7 @@ CONTENT_EXPORT extern const char kDisableAcceleratedFixedRootBackground[];
 CONTENT_EXPORT extern const char kDisableAcceleratedLayers[];
 extern const char kDisableAcceleratedOverflowScroll[];
 CONTENT_EXPORT extern const char kDisableAcceleratedPlugins[];
+extern const char kDisableAcceleratedScrollableFrames[];
 CONTENT_EXPORT extern const char kDisableAcceleratedVideo[];
 CONTENT_EXPORT extern const char kDisableAcceleratedVideoDecode[];
 CONTENT_EXPORT extern const char kDisableAltWinstation[];
@@ -45,6 +46,7 @@ CONTENT_EXPORT extern const char kDisableApplicationCache[];
 CONTENT_EXPORT extern const char kDisableAudio[];
 extern const char kDisableBackingStoreLimit[];
 CONTENT_EXPORT extern const char kDisableBrowserPluginCompositing[];
+extern const char kDisableCompositedScrollingForFrames[];
 CONTENT_EXPORT extern const char kDisableCompositingForFixedPosition[];
 CONTENT_EXPORT extern const char kDisableCompositingForTransition[];
 CONTENT_EXPORT extern const char kDisableDatabases[];
diff --git a/content/renderer/render_view_impl.cc b/content/renderer/render_view_impl.cc
index aef0ac7..18ac4b3 100644
--- a/content/renderer/render_view_impl.cc
+++ b/content/renderer/render_view_impl.cc
@@ -31,6 +31,7 @@
 #include "base/strings/sys_string_conversions.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/time/time.h"
+#include "cc/base/switches.h"
 #include "content/child/appcache/appcache_dispatcher.h"
 #include "content/child/appcache/web_application_cache_host_impl.h"
 #include "content/child/child_thread.h"
@@ -606,6 +607,38 @@ static bool ShouldUseAcceleratedCompositingForOverflowScroll(
   return DeviceScaleEnsuresTextQuality(device_scale_factor);
 }
 
+static bool ShouldUseAcceleratedCompositingForScrollableFrames(
+    float device_scale_factor) {
+  const CommandLine& command_line = *CommandLine::ForCurrentProcess();
+
+  if (command_line.HasSwitch(switches::kDisableAcceleratedScrollableFrames))
+    return false;
+
+  if (command_line.HasSwitch(switches::kEnableAcceleratedScrollableFrames))
+    return true;
+
+  if (!cc::switches::IsLCDTextEnabled())
+    return true;
+
+  return DeviceScaleEnsuresTextQuality(device_scale_factor);
+}
+
+static bool ShouldUseCompositedScrollingForFrames(
+    float device_scale_factor) {
+  const CommandLine& command_line = *CommandLine::ForCurrentProcess();
+
+  if (command_line.HasSwitch(switches::kDisableCompositedScrollingForFrames))
+    return false;
+
+  if (command_line.HasSwitch(switches::kEnableCompositedScrollingForFrames))
+    return true;
+
+  if (!cc::switches::IsLCDTextEnabled())
+    return true;
+
+  return DeviceScaleEnsuresTextQuality(device_scale_factor);
+}
+
 static bool ShouldUseTransitionCompositing(float device_scale_factor) {
   const CommandLine& command_line = *CommandLine::ForCurrentProcess();
 
@@ -899,6 +932,10 @@ void RenderViewImpl::Initialize(RenderViewImplParams* params) {
       ShouldUseTransitionCompositing(device_scale_factor_));
   webview()->settings()->setAcceleratedCompositingForFixedRootBackgroundEnabled(
       ShouldUseAcceleratedFixedRootBackground(device_scale_factor_));
+  webview()->settings()->setAcceleratedCompositingForScrollableFramesEnabled(
+      ShouldUseAcceleratedCompositingForScrollableFrames(device_scale_factor_));
+  webview()->settings()->setCompositedScrollingForFramesEnabled(
+      ShouldUseCompositedScrollingForFrames(device_scale_factor_));
 
   ApplyWebPreferences(webkit_preferences_, webview());
 
@@ -6006,6 +6043,11 @@ void RenderViewImpl::SetDeviceScaleFactor(float device_scale_factor) {
     webview()->settings()->
         setAcceleratedCompositingForFixedRootBackgroundEnabled(
             ShouldUseAcceleratedFixedRootBackground(device_scale_factor_));
+    webview()->settings()->setAcceleratedCompositingForScrollableFramesEnabled(
+        ShouldUseAcceleratedCompositingForScrollableFrames(
+            device_scale_factor_));
+    webview()->settings()->setCompositedScrollingForFramesEnabled(
+        ShouldUseCompositedScrollingForFrames(device_scale_factor_));
   }
   if (auto_resize_mode_)
     AutoResizeCompositor();