De-dupe copy requests for tab capture in DelegatedFrameHost.

content/browser/media/capture/video_capture_oracle.cc

Index: content/browser/media/capture/video_capture_oracle.cc
diff --git a/content/browser/media/capture/video_capture_oracle.cc b/content/browser/media/capture/video_capture_oracle.cc
index dad77c72e965da7e79bca59a1417f0b29a09a816..d870837429008c77cb78203a4ed4ff884d6fa785 100644
--- a/content/browser/media/capture/video_capture_oracle.cc
+++ b/content/browser/media/capture/video_capture_oracle.cc
@@ -67,6 +67,8 @@ double FractionFromExpectedFrameRate(base::TimeDelta delta, int frame_rate) {
 VideoCaptureOracle::VideoCaptureOracle(base::TimeDelta min_capture_period)
     : frame_number_(0),
       last_delivered_frame_number_(-1),
+      first_failed_frame_number_(-1),
+      last_failed_frame_number_(-1),
       smoothing_sampler_(min_capture_period,
                          kNumRedundantCapturesOfStaticContent),
       content_sampler_(min_capture_period) {
@@ -120,7 +122,9 @@ bool VideoCaptureOracle::CompleteCapture(int frame_number,
                                          base::TimeTicks* frame_timestamp) {
   // Drop frame if previous frame number is higher.
   if (last_delivered_frame_number_ > frame_number) {
-    LOG(WARNING) << "Out of order frame delivery detected.  Dropping frame.";
+    LOG(WARNING) << "Out of order frame delivery detected (have #"
+                 << frame_number << ", last was #"
+                 << last_delivered_frame_number_ << ").  Dropping frame.";
     return false;
   }
   last_delivered_frame_number_ = frame_number;
@@ -160,6 +164,26 @@ bool VideoCaptureOracle::CompleteCapture(int frame_number,
   return !frame_timestamp->is_null();
 }
 
+void VideoCaptureOracle::CaptureAbortedOrFailed(int frame_number) {
+  VLOG(1) << "Capture aborted/failed for frame #" << frame_number;
+
+  if (frame_number == (last_failed_frame_number_ + 1)) {
+    // Extending consecutive range of failed captures.
+    last_failed_frame_number_ = frame_number;
+  } else {
+    // Starting new consecutive range of failed captures.
+    first_failed_frame_number_ = last_failed_frame_number_ = frame_number;
+  }
+
+  // Account for the case where the newer captures are aborted before an older
+  // capture succeeds.  In this case, the older capture will contain the newest
+  // content and so its timestamp should reflect that.  See
+  // content::DelegatedFrameHost::DidReceiveFrameFromRenderer().
+  const int prior_frame_number = first_failed_frame_number_ - 1;
+  if (prior_frame_number > last_delivered_frame_number_)
+    SetFrameTimestamp(prior_frame_number, GetFrameTimestamp(frame_number));
+}
+
 base::TimeTicks VideoCaptureOracle::GetFrameTimestamp(int frame_number) const {
   DCHECK_LE(frame_number, frame_number_);
   DCHECK_LT(frame_number_ - frame_number, kMaxFrameTimestamps);