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

cc/tiles/image_decode_cache.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CC_TILES_IMAGE_DECODE_CACHE_H_
 #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"
 
 namespace cc {
 
 class TileTask;
 
 // ImageDecodeCache is responsible for generating decode tasks, decoding
 // images, storing images in cache, and being able to return the decoded images
 // when requested.
 
 // ImageDecodeCache is responsible for the following things:
 // 1. Given a DrawImage, it can return an TileTask which when run will
 //    decode and cache the resulting image. If the image does not need a task to
 //    be decoded, then nullptr will be returned. The return value of the
 //    function indicates whether the image was or is going to be locked, so an
 //    unlock will be required.
 // 2. Given a cache key and a DrawImage, it can decode the image and store it in
 //    the cache. Note that it is important that this function is only accessed
 //    via an image decode task.
 // 3. Given a DrawImage, it can return a DecodedDrawImage, which represented the
 //    decoded version of the image. Note that if the image is not in the cache
 //    and it needs to be scaled/decoded, then this decode will happen as part of
 //    getting the image. As such, this should only be accessed from a raster
 //    thread.
 class CC_EXPORT ImageDecodeCache {
  public:
+  enum class TaskType { kInRaster, kOutOfRaster };
+
   // 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,
+                TaskType task_type)
         : prepare_tiles_id(prepare_tiles_id),
-          requesting_tile_bin(requesting_tile_bin) {}
-    TracingInfo() : TracingInfo(0, TilePriority::NOW) {}
+          requesting_tile_bin(requesting_tile_bin),
+          task_type(task_type) {}
+    TracingInfo() : TracingInfo(0, TilePriority::NOW, TaskType::kInRaster) {}

[vmpstr, 2017/06/01 21:40:56]

While here, can you just = default this and put the initializers inline below?
Does that work with const members?

[Khushal, 2017/06/01 23:45:09]

Done.

 
     // 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;
+
+    // Whether the decode is requested as a part of tile rasterization.
+    const TaskType task_type;
   };
 
+  static devtools_instrumentation::ScopedImageDecodeTask::TaskType
+  ToScopedTaskType(TaskType task_type) {
+    using ScopedTaskType =
+        devtools_instrumentation::ScopedImageDecodeTask::TaskType;
+    switch (task_type) {
+      case TaskType::kInRaster:
+        return ScopedTaskType::kInRaster;
+      case TaskType::kOutOfRaster:
+        return ScopedTaskType::kOutOfRaster;
+    }
+    NOTREACHED();
+    return ScopedTaskType::kInRaster;
+  }
+
   virtual ~ImageDecodeCache() {}
 
   // Fill in an TileTask which will decode the given image when run. In
   // case the image is already cached, fills in nullptr. Returns true if the
   // image needs to be unreffed when the caller is finished with it.
   //
   // This is called by the tile manager (on the compositor thread) when creating
   // a raster task.
   virtual bool GetTaskForImageAndRef(const DrawImage& image,
                                      const TracingInfo& tracing_info,
@@ skipping 37 matching lines @@
   // Returns the maximum amount of memory we would be able to lock. This ignores
   // any temporary states, such as throttled, and return the maximum possible
   // memory. It is used as an esimate of whether an image can fit into the
   // locked budget before creating a task.
   virtual size_t GetMaximumMemoryLimitBytes() const = 0;
 };
 
 }  // namespace cc
 
 #endif  // CC_TILES_IMAGE_DECODE_CACHE_H_