cc: Add UMA for tracking decode duration for out of raster decodes.

cc/tiles/image_decode_cache.h

Index: cc/tiles/image_decode_cache.h
diff --git a/cc/tiles/image_decode_cache.h b/cc/tiles/image_decode_cache.h
index 1b550a6b06e411718ea04d79d05d4cd6f351251d..93377575a7362f81b5618b8aa80405a55b0b5849 100644
--- a/cc/tiles/image_decode_cache.h
+++ b/cc/tiles/image_decode_cache.h
@@ -6,6 +6,7 @@
 #define CC_TILES_IMAGE_DECODE_CACHE_H_
 
 #include "base/memory/ref_counted.h"
+#include "cc/base/devtools_instrumentation.h"
 #include "cc/paint/draw_image.h"
 #include "cc/tiles/decoded_draw_image.h"
 #include "cc/tiles/tile_priority.h"
@@ -34,20 +35,44 @@ class TileTask;
 //    thread.
 class CC_EXPORT ImageDecodeCache {
  public:
+  enum class ImageDecodeType { kInRaster, kCheckerImaging, kJSDecode };

[vmpstr, 2017/05/30 20:15:12]

I think we should be consistent wrt to what we call a thing like
CheckerImages/JSDecode vs Software/GPU. Earlier, you had the _decode_ type as
software/gpu and _task_ type as this. Here, it's the _decode_ type that's
checker/js and not the task. It's a bit confusing.

[Khushal, 2017/05/31 18:21:20]

Done.

+
+  static devtools_instrumentation::ScopedImageDecodeTask::DecodeTaskType
+  ToScopedDecodeTaskType(ImageDecodeType decode_type) {
+    using ScopedTaskType =
+        devtools_instrumentation::ScopedImageDecodeTask::DecodeTaskType;
+    switch (decode_type) {
+      case ImageDecodeType::kInRaster:
+        return ScopedTaskType::kInRaster;
+      case ImageDecodeType::kCheckerImaging:
+        return ScopedTaskType::kCheckerImaging;
+      case ImageDecodeType::kJSDecode:
+        return ScopedTaskType::kJSDecode;
+    }
+    NOTREACHED();
+    return ScopedTaskType::kInRaster;
+  }
+
   // This information should be used strictly in tracing, UMA, and any other
   // reporting systems.
   struct TracingInfo {
     TracingInfo(uint64_t prepare_tiles_id,
-                TilePriority::PriorityBin requesting_tile_bin)
+                TilePriority::PriorityBin requesting_tile_bin,
+                ImageDecodeType type)
         : prepare_tiles_id(prepare_tiles_id),
-          requesting_tile_bin(requesting_tile_bin) {}
-    TracingInfo() : TracingInfo(0, TilePriority::NOW) {}
+          requesting_tile_bin(requesting_tile_bin),
+          type(type) {}
+    TracingInfo()
+        : TracingInfo(0, TilePriority::NOW, ImageDecodeType::kInRaster) {}
 
     // ID for the current prepare tiles call.
     const uint64_t prepare_tiles_id;
 
     // The bin of the tile that caused this image to be requested.
     const TilePriority::PriorityBin requesting_tile_bin;
+
+    // The task type for in-raster and out of raster decode tasks.
+    const ImageDecodeType type;
   };
 
   virtual ~ImageDecodeCache() {}
@@ -68,6 +93,7 @@ class CC_EXPORT ImageDecodeCache {
   // the right GPU context for upload.
   virtual bool GetOutOfRasterDecodeTaskForImageAndRef(
       const DrawImage& image,
+      ImageDecodeType decode_type,
       scoped_refptr<TileTask>* task) = 0;
 
   // Unrefs an image. When the tile is finished, this should be called for every