Histograms cleanup: remove histogram no longer needed in Media Controls code.

Bug: 1088918
Change-Id: I18b179b6da4b10a021386d3afb35713de4b5636e
Fixes: 1088918
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2232765Reviewed-by: Brian White <bcwhite@chromium.org>
Commit-Queue: Mounir Lamouri <mlamouri@chromium.org>
Cr-Commit-Position: refs/heads/master@{#776257}

third_party/blink/renderer/modules/media_controls/media_controls_orientation_lock_delegate.cc

@@ -6,7 +6,6 @@
 
 #include <memory>
 
-#include "base/metrics/histogram_functions.h"
 #include "build/build_config.h"
 #include "third_party/blink/public/common/thread_safe_browser_interface_broker_proxy.h"
 #include "third_party/blink/public/platform/task_type.h"
@@ -39,22 +38,6 @@ namespace blink {
 
 namespace {
 
-// These values are persisted to logs. Entries should not be renumbered and
-// numeric values should never be reused.
-enum class MetadataAvailabilityMetrics {
-  kAvailable = 0,  // Available when lock was attempted.
-  kMissing = 1,    // Missing when lock was attempted.
-  kReceived = 2,   // Received after being missing in order to lock.
-
-  // Keep at the end.
-  kMaxValue = kReceived,
-};
-
-void RecordMetadataAvailability(MetadataAvailabilityMetrics metrics) {
-  base::UmaHistogramEnumeration(
-      "Media.Video.FullscreenOrientationLock.MetadataAvailability", metrics);
-}
-
 // WebLockOrientationCallback implementation that will not react to a success
 // nor a failure.
 class DummyScreenOrientationCallback : public WebLockOrientationCallback {
@@ -100,16 +83,10 @@ void MediaControlsOrientationLockDelegate::MaybeLockOrientation() {
   DCHECK(state_ != State::kMaybeLockedFullscreen);
 
   if (VideoElement().getReadyState() == HTMLMediaElement::kHaveNothing) {
-    RecordMetadataAvailability(MetadataAvailabilityMetrics::kMissing);
     state_ = State::kPendingMetadata;
     return;
   }
 
-  if (state_ == State::kPendingMetadata)
-    RecordMetadataAvailability(MetadataAvailabilityMetrics::kReceived);
-  else
-    RecordMetadataAvailability(MetadataAvailabilityMetrics::kAvailable);
-
   state_ = State::kMaybeLockedFullscreen;
 
   if (!GetDocument().domWindow())

tools/metrics/histograms/histograms.xml

@@ -79596,6 +79596,9 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 <histogram name="Media.Video.FullscreenOrientationLock.MetadataAvailability"
     enum="VideoFullscreenOrientationLockMetadataAvailability"
     expires_after="M85">
+  <obsolete>
+    Removed from code as of 06/2020.
+  </obsolete>
   <owner>mlamouri@chromium.org</owner>
   <summary>
     Status of the metadata when attempting to lock the screen orientation for a