cc: Replace some instances of unordered_map with base::flat_map.

cc/paint/discardable_image_map.cc

 // 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.
 
 #include "cc/paint/discardable_image_map.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <limits>
 
 #include "base/containers/adapters.h"
+#include "base/containers/flat_map.h"
 #include "base/memory/ptr_util.h"
 #include "cc/base/math_util.h"
 #include "cc/paint/display_item_list.h"
 #include "third_party/skia/include/core/SkPath.h"
 #include "third_party/skia/include/utils/SkNWayCanvas.h"
 #include "ui/gfx/geometry/rect_conversions.h"
 #include "ui/gfx/skia_util.h"
 
 namespace cc {
 
@@ skipping 33 matching lines @@
 namespace {
 
 // We're using an NWay canvas with no added canvases, so in effect
 // non-overridden functions are no-ops.
 class DiscardableImagesMetadataCanvas : public SkNWayCanvas {
  public:
   DiscardableImagesMetadataCanvas(
       int width,
       int height,
       std::vector<std::pair<DrawImage, gfx::Rect>>* image_set,
-      std::unordered_map<ImageId, gfx::Rect>* image_id_to_rect)
+      base::flat_map<ImageId, gfx::Rect>* image_id_to_rect)
       : SkNWayCanvas(width, height),
         image_set_(image_set),
         image_id_to_rect_(image_id_to_rect),
         canvas_bounds_(SkRect::MakeIWH(width, height)),
         canvas_size_(width, height) {}
 
  protected:
   // we need to "undo" the behavior of SkNWayCanvas, which will try to forward
   // it.
   void onDrawPicture(const SkPicture* picture,
@@ skipping 163 matching lines @@
         matrix.postConcat(ctm);
         // TODO(ericrk): Handle cases where we only need a sub-rect from the
         // image. crbug.com/671821
         AddImage(sk_ref_sp(image), SkRect::MakeFromIRect(image->bounds()),
                  MapRect(ctm, rect), matrix, &paint);
       }
     }
   }
 
   std::vector<std::pair<DrawImage, gfx::Rect>>* image_set_;
-  std::unordered_map<ImageId, gfx::Rect>* image_id_to_rect_;
+  base::flat_map<ImageId, gfx::Rect>* image_id_to_rect_;
   const SkRect canvas_bounds_;
   const gfx::Size canvas_size_;
   std::vector<SkPaint> saved_paints_;
 };
 
 }  // namespace
 
 DiscardableImageMap::DiscardableImageMap() {}
 
 DiscardableImageMap::~DiscardableImageMap() {}
@@ skipping 35 matching lines @@
     DiscardableImageMap* image_map,
     const gfx::Size& bounds)
     : image_map_(image_map),
       metadata_canvas_(image_map->BeginGeneratingMetadata(bounds)) {}
 
 DiscardableImageMap::ScopedMetadataGenerator::~ScopedMetadataGenerator() {
   image_map_->EndGeneratingMetadata();
 }
 
 }  // namespace cc