New resolution change policies for desktop and tab capture.

media/base/video_capture_types.h

Index: media/base/video_capture_types.h
diff --git a/media/base/video_capture_types.h b/media/base/video_capture_types.h
index 463873f0a58daf8c052afd356c0268e774778746..83a8a1ec2778a46595ffc84a1edb1fab6b3c1704 100644
--- a/media/base/video_capture_types.h
+++ b/media/base/video_capture_types.h
@@ -38,15 +38,22 @@ enum VideoPixelFormat {
 enum ResolutionChangePolicy {
   // Capture device outputs a fixed resolution all the time. The resolution of
   // the first frame is the resolution for all frames.
-  // It is implementation specific for the capture device to scale, letter-box
+  // It is implementation-specific for the capture device to scale, letter-box
   // and pillar-box. The only guarantee is that resolution will never change.
-  RESOLUTION_POLICY_FIXED,
+  RESOLUTION_POLICY_FIXED_RESOLUTION,
 
-  // Capture device outputs frames with dynamic resolution. The width and height
-  // will not exceed the maximum dimensions specified. The typical scenario is
-  // the frames will have the same aspect ratio as the original content and
-  // scaled down to fit inside the limit.
-  RESOLUTION_POLICY_DYNAMIC_WITHIN_LIMIT,
+  // Capture device is allowed to output frames of varying resolutions. The
+  // width and height will not exceed the maximum dimensions specified. The
+  // aspect ratio of the frames will be fixed to the aspect ratio of the maximum
+  // dimensions.
+  // It is implementation-specific for the capture device to scale, letter-box

[mcasas, 2015/05/07 22:10:00]

nit: I'd refactor this comment out, somehow saying that it applies to
both _FIXED_ polcies, otherwise is repeated verbatim.

[miu, 2015/05/08 06:43:34]

Done.

+  // and pillar-box. The only guarantee is that the aspect ratio will never
+  // change.
+  RESOLUTION_POLICY_FIXED_ASPECT_RATIO,
+
+  // Capture device is allowed to output frames of varying resolutions not
+  // exceeding the maximum dimensions specified.
+  RESOLUTION_POLICY_ANY_WITHIN_LIMIT,

[mcasas, 2015/05/07 22:10:00]

IIUC, only Desktop and Tab capture really care about these
division, i.e. the split of ...DYNAMIC_WITHIN_LIMIT into 
...FIXED_ASPECT_RATIO and ...ANY_WITHIN_LIMIT, however, 
I only see ThreadSafeCaptureOracle::UpdateCaptureSize()
and DesktopCaptureDevice::Core::RefreshCaptureFormat()
reacting to RESOLUTION_POLICY_ANY_WITHIN_LIMIT
and not to RESOLUTION_POLICY_FIXED_ASPECT_RATIO,
is this correct?

[miu, 2015/05/08 06:43:34]

Yes, that is correct.  The current implementations will still do the right
thing.  For example, if FIXED_ASPECT_RATIO is specified, they will actually
provide the FIXED_RESOLUTION behavior.  That is acceptable since
FIXED_RESOLUTION frames are all the same aspect ratio.

The whole reason for this change is to support my next CL (probably up for
review tomorrow or Monday).  That's where all three resolution change policies
will be implemented for desktop and tab capture.  See linked bug for details of
what this is all about.

 
   RESOLUTION_POLICY_LAST,
 };
@@ -77,6 +84,12 @@ class MEDIA_EXPORT VideoCaptureFormat {
   // in media::Limits.
   bool IsValid() const;
 
+  bool operator==(const VideoCaptureFormat& other) const {
+    return frame_size == other.frame_size &&
+        frame_rate == other.frame_rate &&
+        pixel_format == other.pixel_format;
+  }
+
   gfx::Size frame_size;
   float frame_rate;
   VideoPixelFormat pixel_format;
@@ -92,6 +105,11 @@ class MEDIA_EXPORT VideoCaptureParams {
  public:
   VideoCaptureParams();
 
+  bool operator==(const VideoCaptureParams& other) const {
+    return requested_format == other.requested_format &&
+        resolution_change_policy == other.resolution_change_policy;
+  }
+
   // Requests a resolution and format at which the capture will occur.
   VideoCaptureFormat requested_format;