GpuVideoAcceleratorFactories: moar constness

Minor cleanups around GVAF & co:
 - const/constexpr
 - early return
 - use = default iso {} [1]

Otherwise no new code, unit tests and such should
cover it all.

[1] https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/qgU4mh_MpGA

Bug: 803975
Change-Id: I7a14a28a3b7ee3703885e40ec0829cc6b4453592
Reviewed-on: https://chromium-review.googlesource.com/897707
Commit-Queue: Miguel Casas <mcasas@chromium.org>
Reviewed-by: Emircan Uysaler <emircan@chromium.org>
Reviewed-by: Xiaohan Wang <xhwang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#534202}

content/renderer/media/gpu/gpu_video_accelerator_factories_impl.cc

@@ -271,10 +271,8 @@ GpuVideoAcceleratorFactoriesImpl::CreateGpuMemoryBuffer(
     const gfx::Size& size,
     gfx::BufferFormat format,
     gfx::BufferUsage usage) {
-  std::unique_ptr<gfx::GpuMemoryBuffer> buffer =
-      gpu_memory_buffer_manager_->CreateGpuMemoryBuffer(
-          size, format, usage, gpu::kNullSurfaceHandle);
-  return buffer;
+  return gpu_memory_buffer_manager_->CreateGpuMemoryBuffer(
+      size, format, usage, gpu::kNullSurfaceHandle);
 }
 bool GpuVideoAcceleratorFactoriesImpl::ShouldUseGpuMemoryBuffersForVideoFrames()
     const {

content/renderer/media/gpu/gpu_video_accelerator_factories_impl.h

@@ -123,9 +123,9 @@ class CONTENT_EXPORT GpuVideoAcceleratorFactoriesImpl
   void BindVideoEncodeAcceleratorProviderOnTaskRunner(
       media::mojom::VideoEncodeAcceleratorProviderPtrInfo unbound_vea_provider);
 
-  scoped_refptr<base::SingleThreadTaskRunner> main_thread_task_runner_;
-  scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
-  scoped_refptr<gpu::GpuChannelHost> gpu_channel_host_;
+  const scoped_refptr<base::SingleThreadTaskRunner> main_thread_task_runner_;
+  const scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
+  const scoped_refptr<gpu::GpuChannelHost> gpu_channel_host_;
 
   // Shared pointer to a shared context provider that should be accessed
   // and set only on the main thread.
@@ -137,7 +137,7 @@ class CONTENT_EXPORT GpuVideoAcceleratorFactoriesImpl
   base::UnguessableToken channel_token_;
 
   // Whether gpu memory buffers should be used to hold video frames data.
-  bool enable_gpu_memory_buffer_video_frames_;
+  const bool enable_gpu_memory_buffer_video_frames_;
   // Whether video acceleration encoding/decoding should be enabled.
   const bool video_accelerator_enabled_;
 

media/video/gpu_memory_buffer_video_frame_pool.cc

@@ -188,7 +188,7 @@ namespace {
 
 // VideoFrame copies to GpuMemoryBuffers will be split in copies where the
 // output size is |kBytesPerCopyTarget| bytes and run in parallel.
-const size_t kBytesPerCopyTarget = 1024 * 1024;  // 1MB
+constexpr size_t kBytesPerCopyTarget = 1024 * 1024;  // 1MB
 
 // Return the GpuMemoryBuffer format to use for a specific VideoPixelFormat
 // and plane.

media/video/gpu_video_accelerator_factories.h

@@ -55,9 +55,10 @@ class MEDIA_EXPORT GpuVideoAcceleratorFactories {
  public:
   class ScopedGLContextLock {
    public:
-    ScopedGLContextLock() {}
+    ScopedGLContextLock() = default;
+    virtual ~ScopedGLContextLock() = default;
+
     virtual gpu::gles2::GLES2Interface* ContextGL() = 0;
-    virtual ~ScopedGLContextLock(){};
 
    private:
     DISALLOW_COPY_AND_ASSIGN(ScopedGLContextLock);
@@ -144,7 +145,7 @@ class MEDIA_EXPORT GpuVideoAcceleratorFactories {
 
  protected:
   friend class base::RefCounted<GpuVideoAcceleratorFactories>;
-  virtual ~GpuVideoAcceleratorFactories() {}
+  virtual ~GpuVideoAcceleratorFactories() = default;
 };
 
 }  // namespace media

media/video/mock_gpu_video_accelerator_factories.h

@@ -68,8 +68,7 @@ class MockGpuVideoAcceleratorFactories : public GpuVideoAcceleratorFactories {
     return video_frame_output_format_;
   };
 
-  std::unique_ptr<GpuVideoAcceleratorFactories::ScopedGLContextLock>
-  GetGLContextLock() override;
+  std::unique_ptr<ScopedGLContextLock> GetGLContextLock() override;
 
   void SetVideoFrameOutputFormat(const OutputFormat video_frame_output_format) {
     video_frame_output_format_ = video_frame_output_format;