Enable disabling WebCore::GraphicsContext in telemetry.

Plumb a flag through from telemetry tests to the layer
painting code that disables the WebCore::GraphicsContext.
This allows us to isolate the various systems that paint
web content in Chromium.

R=nduca@chromium.org,skyostil@chromium.org
BUG=350684

Review URL: https://codereview.chromium.org/253013003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@267913 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 28 insertions, 18 deletions

diff --git a/cc/resources/picture.cc b/cc/resources/picture.cc
index de6ff93..d9b45df 100644
--- a/cc/resources/picture.cc
+++ b/cc/resources/picture.cc
@@ -273,17 +273,23 @@ void Picture::Record(ContentLayerClient* painter,
                               &factory,
                               SkPicture::kUsePathBoundsForClip_RecordingFlag));
 
+  ContentLayerClient::GraphicsContextStatus graphics_context_status =
+      ContentLayerClient::GRAPHICS_CONTEXT_ENABLED;
+
   switch (recording_mode) {
     case RECORD_NORMALLY:
-      // Already setup for normal recording
+      // Already setup for normal recording.
       break;
     case RECORD_WITH_SK_NULL_CANVAS:
       canvas = skia::AdoptRef(SkCreateNullCanvas());
       break;
     case RECORD_WITH_PAINTING_DISABLED:
-      // Blink's GraphicsContext will disable painting when given a NULL
-      // canvas.
-      canvas.clear();
+      // We pass a disable flag through the paint calls when perfromance
+      // testing (the only time this case should ever arise) when we want to
+      // prevent the Blink GraphicsContext object from consuming any compute
+      // time.
+      canvas = skia::AdoptRef(SkCreateNullCanvas());
+      graphics_context_status = ContentLayerClient::GRAPHICS_CONTEXT_DISABLED;
       break;
     case RECORD_WITH_SKRECORD:
       recording.reset(new EXPERIMENTAL::SkRecording(layer_rect_.width(),
@@ -294,23 +300,21 @@ void Picture::Record(ContentLayerClient* painter,
       NOTREACHED();
   }
 
-  if (canvas) {
-    canvas->save();
-    canvas->translate(SkFloatToScalar(-layer_rect_.x()),
-                      SkFloatToScalar(-layer_rect_.y()));
+  canvas->save();
+  canvas->translate(SkFloatToScalar(-layer_rect_.x()),
+                    SkFloatToScalar(-layer_rect_.y()));
 
-    SkRect layer_skrect = SkRect::MakeXYWH(layer_rect_.x(),
-                                           layer_rect_.y(),
-                                           layer_rect_.width(),
-                                           layer_rect_.height());
-    canvas->clipRect(layer_skrect);
-  }
+  SkRect layer_skrect = SkRect::MakeXYWH(layer_rect_.x(),
+                                         layer_rect_.y(),
+                                         layer_rect_.width(),
+                                         layer_rect_.height());
+  canvas->clipRect(layer_skrect);
 
   gfx::RectF opaque_layer_rect;
-  painter->PaintContents(canvas.get(), layer_rect_, &opaque_layer_rect);
+  painter->PaintContents(
+      canvas.get(), layer_rect_, &opaque_layer_rect, graphics_context_status);
 
-  if (canvas)
-    canvas->restore();
+  canvas->restore();
   picture_ = skia::AdoptRef(recorder.endRecording());
   DCHECK(picture_);
 
diff --git a/cc/resources/picture_unittest.cc b/cc/resources/picture_unittest.cc
index a3910c6..61b048a 100644
--- a/cc/resources/picture_unittest.cc
+++ b/cc/resources/picture_unittest.cc
@@ -463,6 +463,8 @@ TEST(PictureTest, RecordingModes) {
                                                    0,
                                                    Picture::RECORD_NORMALLY);
   EXPECT_TRUE(content_layer_client.last_canvas() != NULL);
+  EXPECT_EQ(ContentLayerClient::GRAPHICS_CONTEXT_ENABLED,
+            content_layer_client.last_context_status());
   EXPECT_TRUE(picture);
 
   picture = Picture::Create(layer_rect,
@@ -472,6 +474,8 @@ TEST(PictureTest, RecordingModes) {
                             0,
                             Picture::RECORD_WITH_SK_NULL_CANVAS);
   EXPECT_TRUE(content_layer_client.last_canvas() != NULL);
+  EXPECT_EQ(ContentLayerClient::GRAPHICS_CONTEXT_ENABLED,
+            content_layer_client.last_context_status());
   EXPECT_TRUE(picture);
 
   picture = Picture::Create(layer_rect,
@@ -480,7 +484,9 @@ TEST(PictureTest, RecordingModes) {
                             false,
                             0,
                             Picture::RECORD_WITH_PAINTING_DISABLED);
-  EXPECT_EQ(NULL, content_layer_client.last_canvas());
+  EXPECT_TRUE(content_layer_client.last_canvas() != NULL);
+  EXPECT_EQ(ContentLayerClient::GRAPHICS_CONTEXT_DISABLED,
+            content_layer_client.last_context_status());
   EXPECT_TRUE(picture);
 
   picture = Picture::Create(layer_rect,