Add UMA stats for time in paint+layout, compositing, paint invalidation and paint.

third_party/WebKit/Source/platform/blink_platform.gypi

 {
   'includes': [
     'platform_generated.gypi',
   ],
   'variables': {
     'platform_files': [
       'AsyncFileSystemCallbacks.h',
       'CalculationValue.h',
       'CheckedInt.h',
       'ContentDecryptionModuleResult.h',
@@ skipping 1091 matching lines @@
       'weborigin/SecurityOrigin.h',
       'weborigin/SecurityOriginCache.h',
       'weborigin/SecurityOriginHash.h',
       'weborigin/SecurityPolicy.cpp',
       'weborigin/SecurityPolicy.h',
     ],
     'platform_test_files': [
       'DecimalTest.cpp',
       'DragImageTest.cpp',
       'JSONParserTest.cpp',
+      'HistogramTest.cpp',
       'LayoutUnitTest.cpp',
       'LifecycleContextTest.cpp',
       'PODArenaTest.cpp',
       'PODFreeListArenaTest.cpp',
       'PODIntervalTreeTest.cpp',
       'PODRedBlackTreeTest.cpp',
       'PurgeableVectorTest.cpp',
       'SharedBufferTest.cpp',
       'TimerTest.cpp',
       'TracedValueTest.cpp',
@@ skipping 151 matching lines @@
       ['OS!="mac"',
         {
           'platform_test_files': [
             'scroll/ScrollAnimatorTest.cpp',
           ],
         }
       ],
     ],
   },
 }