Add flag for enabling/disabling video fullscreen detection

chrome/browser/chrome_content_browser_client.cc

Index: chrome/browser/chrome_content_browser_client.cc
diff --git a/chrome/browser/chrome_content_browser_client.cc b/chrome/browser/chrome_content_browser_client.cc
index aa0fee8c2f08847b4a5645c8e42ef9096e57355b..b8bc942dc7eafff1bf97504d81247a9ea03ed286 100644
--- a/chrome/browser/chrome_content_browser_client.cc
+++ b/chrome/browser/chrome_content_browser_client.cc
@@ -247,6 +247,7 @@
 #elif defined(OS_LINUX)
 #include "chrome/browser/chrome_browser_main_linux.h"
 #elif defined(OS_ANDROID)
+#include "chrome/browser/android/app_hooks.h"
 #include "chrome/browser/chrome_browser_main_android.h"
 #include "chrome/common/descriptors_android.h"
 #include "components/crash/content/browser/crash_dump_manager_android.h"
@@ -2682,6 +2683,11 @@ void ChromeContentBrowserClient::OverrideWebkitPrefs(
       }
     }
   }
+
+  if (!command_line->HasSwitch(switches::kDisableVideoFullscreenDetection)) {
+    web_prefs->video_fullscreen_detection_enabled =
+        chrome::android::AppHooks::ShouldDetectVideoFullscreen();
+  }

[mlamouri (slow - plz ping), 2017/03/14 12:02:24]

I don't think we need that flag. WebView doesn't use chrome/browser/ and the
pref is `false` by default. If someone doesn't want the feature.
`ShouldDetectVideoFullscreen()` should return `false`. If that's not called, it
would be `false` anyway.

[Zhiqiang Zhang (Slow), 2017/03/14 13:15:28]

Done.

 #endif  // defined(OS_ANDROID)
 
   for (size_t i = 0; i < extra_parts_.size(); ++i)