media/base: Export IsStorageTypeMappable().

IsStorageTypeMappable() was defined and used in video_frame.cc only.
Export it as VideoFrame::IsStorageTypeMappable() to use in other
places.

BUG=None
TEST=Pass CQ.

Change-Id: Ib3bcf5291e64464c8a75f0e9c5fe2f4c62b179d5
Reviewed-on: https://chromium-review.googlesource.com/c/1356459Reviewed-by: Dale Curtis <dalecurtis@chromium.org>
Commit-Queue: Shuo-Peng Liao <deanliao@google.com>
Cr-Commit-Position: refs/heads/master@{#613010}

media/base/video_frame.cc

@@ -78,9 +78,8 @@ static std::string StorageTypeToString(
   return "INVALID";
 }
 
-// Returns true if |frame| is accesible mapped in the VideoFrame memory space.
 // static
-static bool IsStorageTypeMappable(VideoFrame::StorageType storage_type) {
+bool VideoFrame::IsStorageTypeMappable(VideoFrame::StorageType storage_type) {
   return
 #if defined(OS_LINUX)
       // This is not strictly needed but makes explicit that, at VideoFrame

media/base/video_frame.h

@@ -344,6 +344,10 @@ class MEDIA_EXPORT VideoFrame : public base::RefCountedThreadSafe<VideoFrame> {
   static void HashFrameForTesting(base::MD5Context* context,
                                   const scoped_refptr<VideoFrame>& frame);
 
+  // Returns true if |frame| is accesible mapped in the VideoFrame memory space.
+  // static
+  static bool IsStorageTypeMappable(VideoFrame::StorageType storage_type);
+
   // Returns true if |frame| is accessible and mapped in the VideoFrame memory
   // space. If false, clients should refrain from accessing data(),
   // visible_data() etc.