MSE: Increase log visibility when unfragmented MP4 causes parse failure

Adds an error log entry to chrome://media-internals when MSE's
MP4 stream parser detects an unfragmented MP4. This error log should
help make it more clear why the parse fails in this unfortunately common
case.

BUG=487410
R=dalecurtis,chcunningham
TEST=Manually verified the log entry occurs for the repro in bug 487410.

Review URL: https://codereview.chromium.org/1147453002

Cr-Commit-Position: refs/heads/master@{#330178}

media/formats/mp4/box_definitions.cc

@@ -657,12 +657,15 @@ Movie::~Movie() {}
 FourCC Movie::BoxType() const { return FOURCC_MOOV; }
 
 bool Movie::Parse(BoxReader* reader) {
-  return reader->ScanChildren() &&
-         reader->ReadChild(&header) &&
-         reader->ReadChildren(&tracks) &&
-         // Media Source specific: 'mvex' required
-         reader->ReadChild(&extends) &&
-         reader->MaybeReadChildren(&pssh);
+  RCHECK(reader->ScanChildren() && reader->ReadChild(&header) &&
+         reader->ReadChildren(&tracks));
+
+  RCHECK_MEDIA_LOGGED(reader->ReadChild(&extends), reader->log_cb(),
+                      "Detected unfragmented MP4. Media Source Extensions "
+                      "require ISO BMFF moov to contain mvex to indicate that "
+                      "Movie Fragments are to be expected.");
+
+  return reader->MaybeReadChildren(&pssh);
 }
 
 TrackFragmentDecodeTime::TrackFragmentDecodeTime() : decode_time(0) {}

media/formats/mp4/box_definitions.h

@@ -11,6 +11,7 @@
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "media/base/media_export.h"
+#include "media/base/media_log.h"
 #include "media/formats/mp4/aac.h"
 #include "media/formats/mp4/avc.h"
 #include "media/formats/mp4/box_reader.h"

media/formats/mp4/box_reader.cc

@@ -219,7 +219,8 @@ bool BoxReader::ReadHeader(bool* err) {
   CHECK(Read4Into8(&size) && ReadFourCC(&type_));
 
   if (size == 0) {
-    // Media Source specific: we do not support boxes that run to EOS.
+    MEDIA_LOG(DEBUG, log_cb_) << "Media Source Extensions do not support ISO "
+                                 "BMFF boxes that run to EOS";
     *err = true;
     return false;
   } else if (size == 1) {

media/formats/mp4/box_reader.h

@@ -22,7 +22,10 @@ class BoxReader;
 
 struct MEDIA_EXPORT Box {
   virtual ~Box();
+
+  // Parse errors may be logged using the BoxReader's log callback.
   virtual bool Parse(BoxReader* reader) = 0;
+
   virtual FourCC BoxType() const = 0;
 };
 

media/formats/mp4/rcheck.h

@@ -6,13 +6,25 @@
 #define MEDIA_FORMATS_MP4_RCHECK_H_
 
 #include "base/logging.h"
+#include "media/base/media_log.h"
 
-#define RCHECK(x) \
-    do { \
-      if (!(x)) { \
-        DLOG(ERROR) << "Failure while parsing MP4: " << #x; \
-        return false; \
-      } \
-    } while (0)
+#define RCHECK_MEDIA_LOGGED(condition, log_cb, msg)                 \
+  do {                                                              \
+    if (!(condition)) {                                             \
+      DLOG(ERROR) << "Failure while parsing MP4: " #condition;      \
+      MEDIA_LOG(ERROR, log_cb) << "Failure parsing MP4: " << (msg); \
+      return false;                                                 \
+    }                                                               \
+  } while (0)
+
+// TODO(wolenetz,chcunningham): Where appropriate, replace usage of this macro
+// in favor of RCHECK_MEDIA_LOGGED. See https://crbug.com/487410.
+#define RCHECK(condition)                                      \
+  do {                                                         \
+    if (!(condition)) {                                        \
+      DLOG(ERROR) << "Failure while parsing MP4: " #condition; \
+      return false;                                            \
+    }                                                          \
+  } while (0)
 
 #endif  // MEDIA_FORMATS_MP4_RCHECK_H_