cc: Remove some unnecessary const scoped_refptr&.

This patch makes the API a bit clearer by taking a copy of scoped_refptr
in some situations (where ownership is shared) and using a raw pointer
in situations where ownership is not needed. The only references that
remain are the ones captured in lambdas or Callbacks.

R=danakj
BUG=589044
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review URL: https://codereview.chromium.org/1803863003

Cr-Commit-Position: refs/heads/master@{#381524}

6 files changed, 37 insertions, 41 deletions

diff --git a/cc/output/output_surface.cc b/cc/output/output_surface.cc
index 85372ce..5698635 100644
--- a/cc/output/output_surface.cc
+++ b/cc/output/output_surface.cc
@@ -119,12 +119,12 @@ class SkiaGpuTraceMemoryDump : public SkTraceMemoryDump {
 }  // namespace
 
 OutputSurface::OutputSurface(
-    const scoped_refptr<ContextProvider>& context_provider,
-    const scoped_refptr<ContextProvider>& worker_context_provider,
+    scoped_refptr<ContextProvider> context_provider,
+    scoped_refptr<ContextProvider> worker_context_provider,
     scoped_ptr<SoftwareOutputDevice> software_device)
     : client_(NULL),
-      context_provider_(context_provider),
-      worker_context_provider_(worker_context_provider),
+      context_provider_(std::move(context_provider)),
+      worker_context_provider_(std::move(worker_context_provider)),
       software_device_(std::move(software_device)),
       device_scale_factor_(-1),
       has_alpha_(true),
@@ -133,24 +133,24 @@ OutputSurface::OutputSurface(
   client_thread_checker_.DetachFromThread();
 }
 
-OutputSurface::OutputSurface(
-    const scoped_refptr<ContextProvider>& context_provider)
-    : OutputSurface(context_provider, nullptr, nullptr) {
-}
+OutputSurface::OutputSurface(scoped_refptr<ContextProvider> context_provider)
+    : OutputSurface(std::move(context_provider), nullptr, nullptr) {}
 
 OutputSurface::OutputSurface(
-    const scoped_refptr<ContextProvider>& context_provider,
-    const scoped_refptr<ContextProvider>& worker_context_provider)
-    : OutputSurface(context_provider, worker_context_provider, nullptr) {
-}
+    scoped_refptr<ContextProvider> context_provider,
+    scoped_refptr<ContextProvider> worker_context_provider)
+    : OutputSurface(std::move(context_provider),
+                    std::move(worker_context_provider),
+                    nullptr) {}
 
 OutputSurface::OutputSurface(scoped_ptr<SoftwareOutputDevice> software_device)
     : OutputSurface(nullptr, nullptr, std::move(software_device)) {}
 
-OutputSurface::OutputSurface(
-    const scoped_refptr<ContextProvider>& context_provider,
-    scoped_ptr<SoftwareOutputDevice> software_device)
-    : OutputSurface(context_provider, nullptr, std::move(software_device)) {}
+OutputSurface::OutputSurface(scoped_refptr<ContextProvider> context_provider,
+                             scoped_ptr<SoftwareOutputDevice> software_device)
+    : OutputSurface(std::move(context_provider),
+                    nullptr,
+                    std::move(software_device)) {}
 
 void OutputSurface::CommitVSyncParameters(base::TimeTicks timebase,
                                           base::TimeDelta interval) {
diff --git a/cc/output/output_surface.h b/cc/output/output_surface.h
index 04a105c..64cb19e 100644
--- a/cc/output/output_surface.h
+++ b/cc/output/output_surface.h
@@ -45,17 +45,16 @@ class OutputSurfaceClient;
 //      surface (on the compositor thread) and go back to step 1.
 class CC_EXPORT OutputSurface : public base::trace_event::MemoryDumpProvider {
  public:
-  OutputSurface(const scoped_refptr<ContextProvider>& context_provider,
-                const scoped_refptr<ContextProvider>& worker_context_provider,
+  OutputSurface(scoped_refptr<ContextProvider> context_provider,
+                scoped_refptr<ContextProvider> worker_context_provider,
                 scoped_ptr<SoftwareOutputDevice> software_device);
-  OutputSurface(const scoped_refptr<ContextProvider>& context_provider,
-                const scoped_refptr<ContextProvider>& worker_context_provider);
-  explicit OutputSurface(
-      const scoped_refptr<ContextProvider>& context_provider);
+  OutputSurface(scoped_refptr<ContextProvider> context_provider,
+                scoped_refptr<ContextProvider> worker_context_provider);
+  explicit OutputSurface(scoped_refptr<ContextProvider> context_provider);
 
   explicit OutputSurface(scoped_ptr<SoftwareOutputDevice> software_device);
 
-  OutputSurface(const scoped_refptr<ContextProvider>& context_provider,
+  OutputSurface(scoped_refptr<ContextProvider> context_provider,
                 scoped_ptr<SoftwareOutputDevice> software_device);
 
   ~OutputSurface() override;
diff --git a/cc/output/renderer_pixeltest.cc b/cc/output/renderer_pixeltest.cc
index 7f5bbfd..a953a92 100644
--- a/cc/output/renderer_pixeltest.cc
+++ b/cc/output/renderer_pixeltest.cc
@@ -272,7 +272,7 @@ void CreateTestYUVVideoDrawQuad_FromVideoFrame(
 
 // Upshift video frame to 10 bit.
 scoped_refptr<media::VideoFrame> CreateHighbitVideoFrame(
-    const scoped_refptr<media::VideoFrame>& video_frame) {
+    media::VideoFrame* video_frame) {
   media::VideoPixelFormat format;
   switch (video_frame->format()) {
     case media::PIXEL_FORMAT_I420:
@@ -358,7 +358,7 @@ void CreateTestYUVVideoDrawQuad_Striped(
   uint8_t alpha_value = is_transparent ? 0 : 128;
 
   if (highbit)
-    video_frame = CreateHighbitVideoFrame(video_frame);
+    video_frame = CreateHighbitVideoFrame(video_frame.get());
 
   CreateTestYUVVideoDrawQuad_FromVideoFrame(
       shared_state, video_frame, alpha_value, tex_coord_rect, render_pass,
diff --git a/cc/output/renderer_unittest.cc b/cc/output/renderer_unittest.cc
index 3c8b0b8..1648aec 100644
--- a/cc/output/renderer_unittest.cc
+++ b/cc/output/renderer_unittest.cc
@@ -18,8 +18,7 @@ namespace {
 
 class TestOutputSurface : public OutputSurface {
  public:
-  explicit TestOutputSurface(
-      const scoped_refptr<ContextProvider>& context_provider);
+  explicit TestOutputSurface(scoped_refptr<ContextProvider> context_provider);
   ~TestOutputSurface() override;
 
   // OutputSurface implementation
@@ -27,9 +26,8 @@ class TestOutputSurface : public OutputSurface {
 };
 
 TestOutputSurface::TestOutputSurface(
-    const scoped_refptr<ContextProvider>& context_provider)
-    : OutputSurface(context_provider) {
-}
+    scoped_refptr<ContextProvider> context_provider)
+    : OutputSurface(std::move(context_provider)) {}
 
 TestOutputSurface::~TestOutputSurface() {
 }
diff --git a/cc/output/texture_mailbox_deleter.cc b/cc/output/texture_mailbox_deleter.cc
index 2bef8eb..1310fe7 100644
--- a/cc/output/texture_mailbox_deleter.cc
+++ b/cc/output/texture_mailbox_deleter.cc
@@ -40,8 +40,8 @@ static void PostTaskFromMainToImplThread(
 }
 
 TextureMailboxDeleter::TextureMailboxDeleter(
-    const scoped_refptr<base::SingleThreadTaskRunner>& task_runner)
-    : impl_task_runner_(task_runner), weak_ptr_factory_(this) {}
+    scoped_refptr<base::SingleThreadTaskRunner> task_runner)
+    : impl_task_runner_(std::move(task_runner)), weak_ptr_factory_(this) {}
 
 TextureMailboxDeleter::~TextureMailboxDeleter() {
   for (size_t i = 0; i < impl_callbacks_.size(); ++i)
@@ -49,15 +49,14 @@ TextureMailboxDeleter::~TextureMailboxDeleter() {
 }
 
 scoped_ptr<SingleReleaseCallback> TextureMailboxDeleter::GetReleaseCallback(
-    const scoped_refptr<ContextProvider>& context_provider,
+    scoped_refptr<ContextProvider> context_provider,
     unsigned texture_id) {
-  // This callback owns a reference on the |context_provider|. It must be
-  // destroyed on the impl thread. Upon destruction of this class, the
-  // callback must immediately be destroyed.
+  // This callback owns the |context_provider|. It must be destroyed on the impl
+  // thread. Upon destruction of this class, the callback must immediately be
+  // destroyed.
   scoped_ptr<SingleReleaseCallback> impl_callback =
-      SingleReleaseCallback::Create(base::Bind(&DeleteTextureOnImplThread,
-                                               context_provider,
-                                               texture_id));
+      SingleReleaseCallback::Create(base::Bind(
+          &DeleteTextureOnImplThread, std::move(context_provider), texture_id));
 
   impl_callbacks_.push_back(std::move(impl_callback));
 
diff --git a/cc/output/texture_mailbox_deleter.h b/cc/output/texture_mailbox_deleter.h
index 051ad34..f25661d 100644
--- a/cc/output/texture_mailbox_deleter.h
+++ b/cc/output/texture_mailbox_deleter.h
@@ -27,7 +27,7 @@ class CC_EXPORT TextureMailboxDeleter {
   // task_runner corresponds with the thread the delete task should be posted
   // to. If null, the delete will happen on the calling thread.
   explicit TextureMailboxDeleter(
-      const scoped_refptr<base::SingleThreadTaskRunner>& task_runner);
+      scoped_refptr<base::SingleThreadTaskRunner> task_runner);
   ~TextureMailboxDeleter();
 
   // Returns a Callback that can be used as the ReleaseCallback for a
@@ -38,7 +38,7 @@ class CC_EXPORT TextureMailboxDeleter {
   // become a no-op and the texture will be deleted immediately on the
   // impl thread, along with dropping the reference to the ContextProvider.
   scoped_ptr<SingleReleaseCallback> GetReleaseCallback(
-      const scoped_refptr<ContextProvider>& context_provider,
+      scoped_refptr<ContextProvider> context_provider,
       unsigned texture_id);
 
  private: