CC: Add command-line flag to disable AA.

This has helped a lot in finding the recent
issues with AA. It's also always disabled on
the Android browser compositor since we do our
own feathered edges there.

BUG=233101,256474,259154

Review URL: https://chromiumcodereview.appspot.com/19236005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@212990 0039d316-1c4b-4281-b951-d872f2087c98

6 files changed, 13 insertions, 3 deletions

diff --git a/cc/base/switches.cc b/cc/base/switches.cc
index 768cfde..2dac58b 100644
--- a/cc/base/switches.cc
+++ b/cc/base/switches.cc
@@ -16,6 +16,10 @@ const char kBackgroundColorInsteadOfCheckerboard[] =
 
 const char kDisableThreadedAnimation[] = "disable-threaded-animation";
 
+// Disables layer-edge anti-aliasing in the compositor.
+const char kDisableCompositedAntialiasing[] =
+    "disable-composited-antialiasing";
+
 // Paint content on the main thread instead of the compositor thread.
 // Overrides the kEnableImplSidePainting flag.
 const char kDisableImplSidePainting[] = "disable-impl-side-painting";
diff --git a/cc/base/switches.h b/cc/base/switches.h
index 00acca8..f87eb53 100644
--- a/cc/base/switches.h
+++ b/cc/base/switches.h
@@ -19,6 +19,7 @@ namespace switches {
 CC_EXPORT extern const char kBackgroundColorInsteadOfCheckerboard[];
 CC_EXPORT extern const char kDisableImplSidePainting[];
 CC_EXPORT extern const char kDisableThreadedAnimation[];
+CC_EXPORT extern const char kDisableCompositedAntialiasing[];
 CC_EXPORT extern const char kEnableImplSidePainting[];
 CC_EXPORT extern const char kEnableTopControlsPositionCalculation[];
 CC_EXPORT extern const char kForceDirectLayerDrawing[];
diff --git a/cc/output/gl_renderer.cc b/cc/output/gl_renderer.cc
index 0133b27..c801553 100644
--- a/cc/output/gl_renderer.cc
+++ b/cc/output/gl_renderer.cc
@@ -1124,8 +1124,10 @@ bool GLRenderer::SetupQuadForAntialiasing(
   bool is_nearest_rect_within_epsilon = is_axis_aligned_in_target &&
       gfx::IsNearestRectWithinDistance(device_layer_quad.BoundingBox(),
                                        kAntiAliasingEpsilon);
-  bool use_aa = !clipped && !is_nearest_rect_within_epsilon && quad->IsEdge();
-
+  bool use_aa = Settings().allow_antialiasing &&
+                !clipped &&
+                !is_nearest_rect_within_epsilon &&
+                quad->IsEdge();
   if (!use_aa)
     return false;
 
diff --git a/cc/output/software_renderer.cc b/cc/output/software_renderer.cc
index c164d52..7eac62f 100644
--- a/cc/output/software_renderer.cc
+++ b/cc/output/software_renderer.cc
@@ -226,7 +226,8 @@ void SoftwareRenderer::DoDrawQuad(DrawingFrame* frame, const DrawQuad* quad) {
                                        quad->IsLeftEdge() &&
                                        quad->IsBottomEdge() &&
                                        quad->IsRightEdge();
-    if (all_four_edges_are_exterior)
+    if (Settings().allow_antialiasing &&
+        all_four_edges_are_exterior)
       current_paint_.setAntiAlias(true);
     current_paint_.setFilterBitmap(true);
   }
diff --git a/cc/trees/layer_tree_settings.cc b/cc/trees/layer_tree_settings.cc
index 8d60efe..b041d8b 100644
--- a/cc/trees/layer_tree_settings.cc
+++ b/cc/trees/layer_tree_settings.cc
@@ -14,6 +14,7 @@ namespace cc {
 
 LayerTreeSettings::LayerTreeSettings()
     : impl_side_painting(false),
+      allow_antialiasing(true),
       throttle_frame_production(true),
       begin_frame_scheduling_enabled(false),
       using_synchronous_renderer_compositor(false),
diff --git a/cc/trees/layer_tree_settings.h b/cc/trees/layer_tree_settings.h
index 69c5eeb..9de5ce9 100644
--- a/cc/trees/layer_tree_settings.h
+++ b/cc/trees/layer_tree_settings.h
@@ -21,6 +21,7 @@ class CC_EXPORT LayerTreeSettings {
   ~LayerTreeSettings();
 
   bool impl_side_painting;
+  bool allow_antialiasing;
   bool throttle_frame_production;
   bool begin_frame_scheduling_enabled;
   bool using_synchronous_renderer_compositor;