[Android] Add spellchecking support in android_webview.

android_webview/lib/main/aw_main_delegate.cc

Index: android_webview/lib/main/aw_main_delegate.cc
diff --git a/android_webview/lib/main/aw_main_delegate.cc b/android_webview/lib/main/aw_main_delegate.cc
index 8bc2e459773d4e112a191aecdd0930e18efa89f6..9f8dd74e8eac389635a2eccf6e9ed1d3efc5b13e 100644
--- a/android_webview/lib/main/aw_main_delegate.cc
+++ b/android_webview/lib/main/aw_main_delegate.cc
@@ -32,6 +32,7 @@
 #include "cc/base/switches.h"
 #include "components/crash/content/app/breakpad_linux.h"
 #include "components/external_video_surface/browser/android/external_video_surface_container_impl.h"
+#include "components/spellcheck/common/spellcheck_switches.h"
 #include "content/public/browser/android/browser_media_player_manager_register.h"
 #include "content/public/browser/browser_main_runner.h"
 #include "content/public/browser/browser_thread.h"
@@ -139,6 +140,10 @@ bool AwMainDelegate::BasicStartupComplete(int* exit_code) {
     cl->AppendSwitch(switches::kDisableRendererBackgrounding);
   }
 
+#if defined(ENABLE_SPELLCHECK)
+  cl->AppendSwitch(spellcheck::switches::kEnableAndroidSpellChecker);

[Tobias Sargeant, 2016/08/23 14:17:58]

I don't think we want to unilaterally enable this initially - I thought the plan
was to set it manually in /data/local/tmp/webview-command-line for testing?

Also, when this flag is enabled, don't we also need to enable the unified editor
flag?

[timvolodine, 2016/08/23 15:29:18]

right sorry forgot to remove this after testing locally. The unified_editor flag
was removed recently in https://codereview.chromium.org/2235643002/, see the
discussion there. 

Although the unified_editor used to be false by default in webview this probably
shouldn't be an issue if we want to enable spellcheck in webview by default
anyway.

+#endif
+
   return false;
 }