Use wtf_size_t for frame index accessing frame buffer cache.

BUG=879657

Change-Id: Ifc3ba15e517c79286158e77a8bb83c3c30ea1a75
Reviewed-on: https://chromium-review.googlesource.com/c/1355881Reviewed-by: Jeremy Roman <jbroman@chromium.org>
Commit-Queue: Dave Tapuska <dtapuska@chromium.org>
Cr-Commit-Position: refs/heads/master@{#612413}

third_party/blink/renderer/platform/image-decoders/image_decoder.h

@@ -443,7 +443,7 @@ class PLATFORM_EXPORT ImageDecoder {
   //
   // Before calling this, verify that frame |index| exists by checking that
   // |index| is smaller than |frame_buffer_cache_|.size().
-  virtual bool FrameStatusSufficientForSuccessors(size_t index) {
+  virtual bool FrameStatusSufficientForSuccessors(wtf_size_t index) {
     DCHECK(index < frame_buffer_cache_.size());
     ImageFrame::Status frame_status = frame_buffer_cache_[index].GetStatus();
     return frame_status == ImageFrame::kFramePartial ||

third_party/blink/renderer/platform/image-decoders/webp/webp_image_decoder.h

@@ -70,7 +70,7 @@ class PLATFORM_EXPORT WEBPImageDecoder final : public ImageDecoder {
   //
   // Before calling this, verify that frame |index| exists by checking that
   // |index| is smaller than |frame_buffer_cache_|.size().
-  bool FrameStatusSufficientForSuccessors(size_t index) override {
+  bool FrameStatusSufficientForSuccessors(wtf_size_t index) override {
     DCHECK(index < frame_buffer_cache_.size());
     return frame_buffer_cache_[index].GetStatus() == ImageFrame::kFrameComplete;
   }