Resolve media/cast crypto crash, and add crash reporting.

media/cast/sender/vp8_encoder.cc

Index: media/cast/sender/vp8_encoder.cc
diff --git a/media/cast/sender/vp8_encoder.cc b/media/cast/sender/vp8_encoder.cc
index 7bb2f11f5ff345e064d0e131df805ff563ed7211..771075a17aa70c66e06ddb08f57a99e6267bb25c 100644
--- a/media/cast/sender/vp8_encoder.cc
+++ b/media/cast/sender/vp8_encoder.cc
@@ -4,7 +4,11 @@
 
 #include "media/cast/sender/vp8_encoder.h"
 
+#include "base/debug/crash_logging.h"
+#include "base/debug/dump_without_crashing.h"
+#include "base/format_macros.h"
 #include "base/logging.h"
+#include "base/strings/stringprintf.h"
 #include "media/base/video_frame.h"
 #include "media/cast/cast_defines.h"
 #include "third_party/libvpx_new/source/libvpx/vpx/vp8cx.h"
@@ -31,7 +35,8 @@ Vp8Encoder::Vp8Encoder(const VideoSenderConfig& video_config)
       bitrate_kbit_(cast_config_.start_bitrate / 1000),
       last_encoded_frame_id_(kStartFrameId),
       last_acked_frame_id_(kStartFrameId),
-      undroppable_frames_(0) {
+      undroppable_frames_(0),
+      has_seen_zero_length_encoded_frame_(false) {
   config_.g_timebase.den = 0;  // Not initialized.
 
   for (int i = 0; i < kNumberOfVp8VideoBuffers; ++i) {
@@ -283,6 +288,24 @@ void Vp8Encoder::Encode(const scoped_refptr<media::VideoFrame>& video_frame,
   DCHECK(!encoded_frame->data.empty())
       << "BUG: Encoder must provide data since lagged encoding is disabled.";
 
+  // TODO(miu): Determine when/why encoding can produce zero-length data,
+  // which causes crypto crashes.  http://crbug.com/519022
+  if (!has_seen_zero_length_encoded_frame_ && encoded_frame->data.empty()) {
+    has_seen_zero_length_encoded_frame_ = true;
+
+    const char kZeroEncodeDetails[] = "zero-encode-details";
+    const std::string details = base::StringPrintf(
+        "SV/%c,id=%" PRIu32 ",rtp=%" PRIu32 ",br=%d,kfr=%c",
+        encoded_frame->dependency == EncodedFrame::KEY ? 'K' : 'D',
+        encoded_frame->frame_id, encoded_frame->rtp_timestamp,
+        static_cast<int>(config_.rc_target_bitrate),
+        key_frame_requested_ ? 'Y' : 'N');
+    base::debug::SetCrashKeyValue(kZeroEncodeDetails, details);
+    // Please forward crash reports to http://crbug.com/519022:
+    base::debug::DumpWithoutCrashing();
+    base::debug::ClearCrashKey(kZeroEncodeDetails);
+  }
+
   // Compute deadline utilization as the real-world time elapsed divided by the
   // frame duration.
   const base::TimeDelta processing_time = base::TimeTicks::Now() - start_time;