Removed unnecessary parameter from didActivateCompositor()

The parameter to didActivateCompositor() is not necessary. Hence, removed it. The other blink side changes are here:
https://codereview.chromium.org/138523003/

BUG=None

Review URL: https://codereview.chromium.org/137893025

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@256713 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 256713
Initial set of changes for loading correctly scaled resources in the PDF Chrome pepper plugin.
We should attempt to load the resource of the supported scale factor based on the scale passed in.

BUG=351542
R=cpu@chromium.org, yzshen@chromium.org, cpu, yzshen

Review URL: https://codereview.chromium.org/196283002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@256714 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 256714