Delete per-layer gpu rasterization hint.

The hint is now per page instead of per layer.

BUG=367202

Review URL: https://codereview.chromium.org/312203002

git-svn-id: svn://svn.chromium.org/blink/trunk@175690 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/public/platform/WebContentLayer.h

@@ -53,8 +53,6 @@ public:
     // for these tiles.
     // Defaults to false.
     virtual void setDrawCheckerboardForMissingTiles(bool) = 0;
-
-    virtual void setHasGpuRasterizationHint(bool) = 0;
 };
 
 } // namespace blink