publish canvas context API stat metrics

third_party/WebKit/Source/platform/blink_platform.gypi

 {
   'includes': [
     'platform_generated.gypi',
   ],
   'variables': {
     'platform_files': [
       'AsyncFileSystemCallbacks.h',
       'CalculationValue.h',
       'CheckedInt.h',
       'Clock.cpp',
@@ skipping 482 matching lines @@
       'geometry/mac/FloatRectMac.mm',
       'geometry/mac/FloatSizeMac.mm',
       'geometry/mac/IntPointMac.mm',
       'geometry/mac/IntRectMac.mm',
       'geometry/mac/IntSizeMac.mm',
       'graphics/BitmapImage.cpp',
       'graphics/BitmapImage.h',
       'graphics/Canvas2DImageBufferSurface.h',
       'graphics/Canvas2DLayerBridge.cpp',
       'graphics/Canvas2DLayerBridge.h',
+      'graphics/CanvasMetrics.h',
+      'graphics/CanvasMetrics.cpp',
       'graphics/Color.cpp',
       'graphics/Color.h',
       'graphics/ColorSpace.cpp',
       'graphics/ColorSpace.h',
       'graphics/CompositingReasons.cpp',
       'graphics/CompositingReasons.h',
       'graphics/ContentLayerDelegate.cpp',
       'graphics/ContentLayerDelegate.h',
       'graphics/ContiguousContainer.cpp',
       'graphics/ContiguousContainer.h',
@@ skipping 593 matching lines @@
       ['OS!="mac"',
         {
           'platform_test_files': [
             'scroll/ScrollAnimatorTest.cpp',
           ],
         }
       ],
     ],
   },
 }