Use media::limits constants in GPU video accelerator stack

* Exynos VDA does not allocate enough buffers to completely fill the pipeline,
  which can lead to decoding hangs.  Use media::limits::kMaxVideoFrames to
  account for this.
* Use media::limits::kMaxDimension and media::limits::kMaxCanvas to set limits
  on frame width/size/area in GpuVideo{Encode,Decode}Accelerator

BUG=None
TEST=build, run on CrOS snow

Review URL: https://chromiumcodereview.appspot.com/23710074

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@225107 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 225107
Modified the input injector to generate a single SendInput() call per one protocol::MouseEvent.

Review URL: https://chromiumcodereview.appspot.com/24067006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@225108 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 225108