Revert "Include image data when reporting UKM from canvas readbacks."

This reverts commit 5bf5f652.

Reason for revert: This cl caused a perf regression in the rendering.mobile and blink_perf.canvas benchmarks.

Bug: 1092434,1087234,973801

Original change's description:
> Include image data when reporting UKM from canvas readbacks.
> 
> This is a reland of https://crrev.com/c/2207979, but which takes extra steps to avoid performance regressions. In particular:
> * No additional overhead is incurred if the user is not in the identifiability study.
> * The overhead of constructing the pixmap is posted to another thread, rather than holding up the current thread.
> 
> Bug: 973801,1087234
> Change-Id: I7701c622e4d146504b1ea57d0f2047aa2a98ed9f
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2224820
> Reviewed-by: Fernando Serboncini <fserb@chromium.org>
> Reviewed-by: Asanka Herath <asanka@chromium.org>
> Commit-Queue: Chris Fredrickson <cfredric@google.com>
> Cr-Commit-Position: refs/heads/master@{#775558}

TBR=fserb@chromium.org,asanka@chromium.org,cfredric@google.com

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 973801, 1087234
Change-Id: I5bc8452692562f8b82af0c3b0903327b86744cc9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2236336Reviewed-by: Fernando Serboncini <fserb@chromium.org>
Commit-Queue: Chris Fredrickson <cfredric@google.com>
Cr-Commit-Position: refs/heads/master@{#776536}

third_party/blink/renderer/core/html/canvas/canvas_async_blob_creator.cc

@@ -8,9 +8,6 @@
 #include "base/metrics/histogram_functions.h"
 #include "base/metrics/histogram_macros.h"
 #include "build/build_config.h"
-#include "third_party/blink/public/common/privacy_budget/identifiability_metric_builder.h"
-#include "third_party/blink/public/common/privacy_budget/identifiability_metrics.h"
-#include "third_party/blink/public/common/privacy_budget/identifiability_study_participation.h"
 #include "third_party/blink/public/platform/platform.h"
 #include "third_party/blink/public/platform/task_type.h"
 #include "third_party/blink/renderer/core/dom/document.h"
@@ -149,7 +146,6 @@ CanvasAsyncBlobCreator::CanvasAsyncBlobCreator(
     ToBlobFunctionType function_type,
     base::TimeTicks start_time,
     ExecutionContext* context,
-    base::Optional<UkmParameters> ukm_params,
     ScriptPromiseResolver* resolver)
     : CanvasAsyncBlobCreator(image,
                              options,
@@ -157,7 +153,6 @@ CanvasAsyncBlobCreator::CanvasAsyncBlobCreator(
                              nullptr,
                              start_time,
                              context,
-                             ukm_params,
                              resolver) {}
 
 CanvasAsyncBlobCreator::CanvasAsyncBlobCreator(
@@ -167,7 +162,6 @@ CanvasAsyncBlobCreator::CanvasAsyncBlobCreator(
     V8BlobCallback* callback,
     base::TimeTicks start_time,
     ExecutionContext* context,
-    base::Optional<UkmParameters> ukm_params,
     ScriptPromiseResolver* resolver)
     : fail_encoder_initialization_for_test_(false),
       enforce_idle_encoding_for_test_(false),
@@ -178,7 +172,6 @@ CanvasAsyncBlobCreator::CanvasAsyncBlobCreator(
       start_time_(start_time),
       static_bitmap_image_loaded_(false),
       callback_(callback),
-      ukm_params_(ukm_params),
       script_promise_resolver_(resolver) {
   DCHECK(image);
   DCHECK(context);
@@ -475,8 +468,6 @@ void CanvasAsyncBlobCreator::CreateBlobAndReturnResult() {
                              WrapPersistent(result_blob)));
   }
 
-  RecordIdentifiabilityMetric();
-
   RecordScaledDurationHistogram(mime_type_,
                                 base::TimeTicks::Now() - start_time_,
                                 image_->width(), image_->height());
@@ -484,33 +475,6 @@ void CanvasAsyncBlobCreator::CreateBlobAndReturnResult() {
   Dispose();
 }
 
-void CanvasAsyncBlobCreator::RecordIdentifiabilityMetric() {
-  if (!ukm_params_.has_value() || !IsUserInIdentifiabilityStudy())
-    return;
-  // Creating this ImageDataBuffer has some overhead, namely getting the SkImage
-  // and computing the pixmap.
-  context_->GetTaskRunner(TaskType::kInternalDefault)
-      ->PostTask(
-          FROM_HERE,
-          WTF::Bind(
-              [](scoped_refptr<StaticBitmapImage> image,
-                 UkmParameters ukm_params) {
-                std::unique_ptr<ImageDataBuffer> data_buffer =
-                    ImageDataBuffer::Create(image);
-                if (!data_buffer)
-                  return;
-                blink::IdentifiabilityMetricBuilder(ukm_params.source_id)
-                    .Set(blink::IdentifiableSurface::FromTypeAndInput(
-                             blink::IdentifiableSurface::Type::kCanvasReadback,
-                             0),
-                         blink::IdentifiabilityDigestOfBytes(
-                             base::make_span(data_buffer->Pixels(),
-                                             data_buffer->ComputeByteSize())))
-                    .Record(ukm_params.ukm_recorder);
-              },
-              image_, ukm_params_.value()));
-}
-
 void CanvasAsyncBlobCreator::CreateNullAndReturnResult() {
   RecordIdleTaskStatusHistogram(idle_task_status_);
   if (function_type_ == kHTMLCanvasToBlobCallback) {

third_party/blink/renderer/core/html/canvas/canvas_async_blob_creator.h

@@ -8,14 +8,11 @@
 #include <memory>
 
 #include "base/location.h"
-#include "base/optional.h"
 #include "base/single_thread_task_runner.h"
-#include "services/metrics/public/cpp/ukm_recorder.h"
 #include "third_party/blink/renderer/bindings/core/v8/script_promise_resolver.h"
 #include "third_party/blink/renderer/bindings/core/v8/v8_blob_callback.h"
 #include "third_party/blink/renderer/bindings/core/v8/v8_image_encode_options.h"
 #include "third_party/blink/renderer/core/core_export.h"
-#include "third_party/blink/renderer/core/html/canvas/ukm_parameters.h"
 #include "third_party/blink/renderer/core/typed_arrays/dom_typed_array.h"
 #include "third_party/blink/renderer/platform/geometry/int_size.h"
 #include "third_party/blink/renderer/platform/graphics/graphics_types.h"
@@ -63,7 +60,6 @@ class CORE_EXPORT CanvasAsyncBlobCreator
                          ToBlobFunctionType function_type,
                          base::TimeTicks start_time,
                          ExecutionContext*,
-                         base::Optional<UkmParameters> ukm_params,
                          ScriptPromiseResolver*);
   CanvasAsyncBlobCreator(scoped_refptr<StaticBitmapImage>,
                          const ImageEncodeOptions*,
@@ -71,7 +67,6 @@ class CORE_EXPORT CanvasAsyncBlobCreator
                          V8BlobCallback*,
                          base::TimeTicks start_time,
                          ExecutionContext*,
-                         base::Optional<UkmParameters> ukm_params,
                          ScriptPromiseResolver* = nullptr);
   virtual ~CanvasAsyncBlobCreator();
 
@@ -137,8 +132,6 @@ class CORE_EXPORT CanvasAsyncBlobCreator
   // Used for HTMLCanvasElement only
   Member<V8BlobCallback> callback_;
 
-  base::Optional<UkmParameters> ukm_params_;
-
   // Used for OffscreenCanvas only
   Member<ScriptPromiseResolver> script_promise_resolver_;
 
@@ -154,8 +147,6 @@ class CORE_EXPORT CanvasAsyncBlobCreator
 
   void IdleTaskStartTimeoutEvent(double quality);
   void IdleTaskCompleteTimeoutEvent();
-
-  void RecordIdentifiabilityMetric();
 };
 
 }  // namespace blink

third_party/blink/renderer/core/html/canvas/canvas_async_blob_creator_test.cc

@@ -35,7 +35,6 @@ class MockCanvasAsyncBlobCreator : public CanvasAsyncBlobCreator {
             nullptr,
             base::TimeTicks(),
             document->GetExecutionContext(),
-            base::make_optional<UkmParameters>(),
             nullptr) {
     if (fail_encoder_initialization)
       fail_encoder_initialization_for_test_ = true;
@@ -130,6 +129,7 @@ class CanvasAsyncBlobCreatorTest : public PageTestBase {
   void TearDown() override;
 
  private:
+
   Persistent<MockCanvasAsyncBlobCreator> async_blob_creator_;
 };
 
@@ -264,8 +264,7 @@ TEST_F(CanvasAsyncBlobCreatorTest, ColorManagedConvertToBlob) {
                                          kDisplayP3ImageColorSpaceName,
                                          kRec2020ImageColorSpaceName};
   std::list<String> blob_pixel_formats = {
-      kRGBA8ImagePixelFormatName,
-      kRGBA16ImagePixelFormatName,
+      kRGBA8ImagePixelFormatName, kRGBA16ImagePixelFormatName,
   };
 
   // Maximum differences are both observed locally with
@@ -296,8 +295,7 @@ TEST_F(CanvasAsyncBlobCreatorTest, ColorManagedConvertToBlob) {
                   source_bitmap_image, options,
                   CanvasAsyncBlobCreator::ToBlobFunctionType::
                       kHTMLCanvasConvertToBlobPromise,
-                  base::TimeTicks(), GetFrame().DomWindow(),
-                  base::make_optional<UkmParameters>(), nullptr);
+                  base::TimeTicks(), GetFrame().DomWindow(), nullptr);
           ASSERT_TRUE(async_blob_creator->EncodeImageForConvertToBlobTest());
 
           sk_sp<SkData> sk_data = SkData::MakeWithCopy(
@@ -328,4 +326,4 @@ TEST_F(CanvasAsyncBlobCreatorTest, ColorManagedConvertToBlob) {
     }
   }
 }
-}  // namespace blink
+}

third_party/blink/renderer/core/html/canvas/canvas_rendering_context_host.cc

@@ -329,7 +329,7 @@ ScriptPromise CanvasRenderingContextHost::convertToBlob(
     }
     auto* async_creator = MakeGarbageCollected<CanvasAsyncBlobCreator>(
         image_bitmap, options, function_type, start_time,
-        ExecutionContext::From(script_state), ukm_params_, resolver);
+        ExecutionContext::From(script_state), resolver);
     async_creator->ScheduleAsyncBlobCreation(options->quality());
     return resolver->Promise();
   }

third_party/blink/renderer/core/html/canvas/html_canvas_element.cc

@@ -377,6 +377,12 @@ ScriptPromise HTMLCanvasElement::convertToBlob(
     ScriptState* script_state,
     const ImageEncodeOptions* options,
     ExceptionState& exception_state) {
+  RecordIdentifiabilityMetric(
+      blink::IdentifiableSurface::FromTypeAndInput(
+          blink::IdentifiableSurface::Type::kCanvasReadback,
+          context_ ? context_->GetContextType()
+                   : CanvasRenderingContext::kContextTypeUnknown),
+      0);
   return CanvasRenderingContextHost::convertToBlob(script_state, options,
                                                    exception_state);
 }
@@ -964,8 +970,7 @@ String HTMLCanvasElement::ToDataURLInternal(
     RecordIdentifiabilityMetric(
         blink::IdentifiableSurface::FromTypeAndInput(
             blink::IdentifiableSurface::Type::kCanvasReadback, final_digest),
-        blink::IdentifiabilityDigestOfBytes(base::make_span(
-            data_buffer->Pixels(), data_buffer->ComputeByteSize())));
+        blink::IdentifiabilityDigestOfBytes(data_url.Span8()));
     return data_url;
   }
 
@@ -1032,11 +1037,16 @@ void HTMLCanvasElement::toBlob(V8BlobCallback* callback,
     async_creator = MakeGarbageCollected<CanvasAsyncBlobCreator>(
         image_bitmap, options,
         CanvasAsyncBlobCreator::kHTMLCanvasToBlobCallback, callback, start_time,
-        GetExecutionContext(),
-        base::make_optional<UkmParameters>(
-            {GetDocument().UkmRecorder(), GetDocument().UkmSourceID()}));
+        GetExecutionContext());
   }
 
+  RecordIdentifiabilityMetric(
+      blink::IdentifiableSurface::FromTypeAndInput(
+          blink::IdentifiableSurface::Type::kCanvasReadback,
+          context_ ? context_->GetContextType()
+                   : CanvasRenderingContext::kContextTypeUnknown),
+      0);
+
   if (async_creator) {
     async_creator->ScheduleAsyncBlobCreation(quality);
   } else {

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

@@ -60,7 +60,6 @@ class PLATFORM_EXPORT ImageDataBuffer {
   const IntSize& size() const { return size_; }
   int Height() const { return size_.Height(); }
   int Width() const { return size_.Width(); }
-  size_t ComputeByteSize() const { return pixmap_.computeByteSize(); }
 
  private:
   ImageDataBuffer(const IntSize&,