Remove Offscreen Canvas Commit Timer histogram.

Deprecate histogram and remove all references.

Bug: 894043
Change-Id: I101f75fc0882a7844a58507a194eb1a5efde207e
Reviewed-on: https://chromium-review.googlesource.com/c/1308755
Commit-Queue: David Quiroz Marin <davidqu@chromium.org>
Reviewed-by: Fernando Serboncini <fserb@chromium.org>
Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Cr-Commit-Position: refs/heads/master@{#604632}

third_party/blink/renderer/platform/graphics/canvas_resource_dispatcher.cc

@@ -226,30 +226,6 @@ bool CanvasResourceDispatcher::PrepareFrame(
   sqs->SetAll(gfx::Transform(), bounds, bounds, bounds, is_clipped, is_opaque,
               1.f, SkBlendMode::kSrcOver, 0);
 
-  OffscreenCanvasCommitType commit_type;
-  if (canvas_resource->IsAccelerated()) {
-    // While |image| is texture backed, it could be generated with "software
-    // rendering" aka swiftshader. If the compositor is not also using
-    // swiftshader, then we could not give a swiftshader based texture
-    // to the compositor. However in that case, IsGpuCompositingEnabled() will
-    // also be false, so we will avoid doing so.
-    if (SharedGpuContext::IsGpuCompositingEnabled()) {
-      // Case 1: both canvas and compositor are gpu accelerated.
-      commit_type = kCommitGPUCanvasGPUCompositing;
-    } else {
-      // Case 2: canvas is accelerated but gpu compositing is disabled.
-      commit_type = kCommitGPUCanvasSoftwareCompositing;
-    }
-  } else {
-    if (SharedGpuContext::IsGpuCompositingEnabled()) {
-      // Case 3: canvas is not gpu-accelerated, but compositor is.
-      commit_type = kCommitSoftwareCanvasGPUCompositing;
-    } else {
-      // Case 4: both canvas and compositor are not gpu accelerated.
-      commit_type = kCommitSoftwareCanvasSoftwareCompositing;
-    }
-  }
-
   viz::TransferableResource resource;
   auto frame_resource = std::make_unique<FrameResource>();
 
@@ -294,92 +270,6 @@ bool CanvasResourceDispatcher::PrepareFrame(
 
   frame->render_pass_list.push_back(std::move(pass));
 
-  base::TimeDelta elapsed_time = WTF::CurrentTimeTicks() - commit_start_time;
-
-  switch (commit_type) {
-    case kCommitGPUCanvasGPUCompositing:
-      if (IsMainThread()) {
-        DEFINE_STATIC_LOCAL(
-            CustomCountHistogram, commit_gpu_canvas_gpu_compositing_main_timer,
-            ("Blink.Canvas.OffscreenCommit.GPUCanvasGPUCompositingMain", 0,
-             10000000, 50));
-        commit_gpu_canvas_gpu_compositing_main_timer.CountMicroseconds(
-            elapsed_time);
-      } else {
-        DEFINE_THREAD_SAFE_STATIC_LOCAL(
-            CustomCountHistogram,
-            commit_gpu_canvas_gpu_compositing_worker_timer,
-            ("Blink.Canvas.OffscreenCommit.GPUCanvasGPUCompositingWorker", 0,
-             10000000, 50));
-        commit_gpu_canvas_gpu_compositing_worker_timer.CountMicroseconds(
-            elapsed_time);
-      }
-      break;
-    case kCommitGPUCanvasSoftwareCompositing:
-      if (IsMainThread()) {
-        DEFINE_STATIC_LOCAL(
-            CustomCountHistogram,
-            commit_gpu_canvas_software_compositing_main_timer,
-            ("Blink.Canvas.OffscreenCommit.GPUCanvasSoftwareCompositingMain", 0,
-             10000000, 50));
-        commit_gpu_canvas_software_compositing_main_timer.CountMicroseconds(
-            elapsed_time);
-      } else {
-        DEFINE_THREAD_SAFE_STATIC_LOCAL(
-            CustomCountHistogram,
-            commit_gpu_canvas_software_compositing_worker_timer,
-            ("Blink.Canvas.OffscreenCommit."
-             "GPUCanvasSoftwareCompositingWorker",
-             0, 10000000, 50));
-        commit_gpu_canvas_software_compositing_worker_timer.CountMicroseconds(
-            elapsed_time);
-      }
-      break;
-    case kCommitSoftwareCanvasGPUCompositing:
-      if (IsMainThread()) {
-        DEFINE_STATIC_LOCAL(
-            CustomCountHistogram,
-            commit_software_canvas_gpu_compositing_main_timer,
-            ("Blink.Canvas.OffscreenCommit.SoftwareCanvasGPUCompositingMain", 0,
-             10000000, 50));
-        commit_software_canvas_gpu_compositing_main_timer.CountMicroseconds(
-            elapsed_time);
-      } else {
-        DEFINE_THREAD_SAFE_STATIC_LOCAL(
-            CustomCountHistogram,
-            commit_software_canvas_gpu_compositing_worker_timer,
-            ("Blink.Canvas.OffscreenCommit."
-             "SoftwareCanvasGPUCompositingWorker",
-             0, 10000000, 50));
-        commit_software_canvas_gpu_compositing_worker_timer.CountMicroseconds(
-            elapsed_time);
-      }
-      break;
-    case kCommitSoftwareCanvasSoftwareCompositing:
-      if (IsMainThread()) {
-        DEFINE_STATIC_LOCAL(
-            CustomCountHistogram,
-            commit_software_canvas_software_compositing_main_timer,
-            ("Blink.Canvas.OffscreenCommit."
-             "SoftwareCanvasSoftwareCompositingMain",
-             0, 10000000, 50));
-        commit_software_canvas_software_compositing_main_timer
-            .CountMicroseconds(elapsed_time);
-      } else {
-        DEFINE_THREAD_SAFE_STATIC_LOCAL(
-            CustomCountHistogram,
-            commit_software_canvas_software_compositing_worker_timer,
-            ("Blink.Canvas.OffscreenCommit."
-             "SoftwareCanvasSoftwareCompositingWorker",
-             0, 10000000, 50));
-        commit_software_canvas_software_compositing_worker_timer
-            .CountMicroseconds(elapsed_time);
-      }
-      break;
-    case kOffscreenCanvasCommitTypeCount:
-      NOTREACHED();
-  }
-
   if (change_size_for_next_commit_) {
     parent_local_surface_id_allocator_.GenerateId();
     change_size_for_next_commit_ = false;

third_party/blink/renderer/platform/graphics/canvas_resource_dispatcher.h

@@ -75,15 +75,6 @@ class PLATFORM_EXPORT CanvasResourceDispatcher
                                ::gpu::mojom::blink::MailboxPtr id);
   void DidDeleteSharedBitmap(::gpu::mojom::blink::MailboxPtr id);
 
-  // This enum is used in histogram, so it should be append-only.
-  enum OffscreenCanvasCommitType {
-    kCommitGPUCanvasGPUCompositing = 0,
-    kCommitGPUCanvasSoftwareCompositing = 1,
-    kCommitSoftwareCanvasGPUCompositing = 2,
-    kCommitSoftwareCanvasSoftwareCompositing = 3,
-    kOffscreenCanvasCommitTypeCount,
-  };
-
  private:
   friend class CanvasResourceDispatcherTest;
   struct FrameResource;

tools/metrics/histograms/histograms.xml

@@ -8846,6 +8846,9 @@ uploading your change for review.
 </histogram>
 
 <histogram name="Blink.Canvas.OffscreenCommitTimer" units="microseconds">
+  <obsolete>
+    Deprecated in 10/2018. Offscreen Canvas no longer needs commits.
+  </obsolete>
   <owner>junov@chromium.org</owner>
   <owner>xidachen@chromium.org</owner>
   <summary>