android_webview: Enable FDO support for some targets.

Enable feedback-directed optimisation for the main library (required to
make the FDO symbols present at link time), skia, and sqlite. Update the
android_exports whitelist to allow the gcov symbols to remain public as
otherwise profiling will fail.

BUG=
TBR=michaeln@chromium.org

Review URL: https://codereview.chromium.org/591153002

Cr-Commit-Position: refs/heads/master@{#296997}

android_webview/libwebviewchromium.gypi

@@ -31,6 +31,11 @@
         '../ui/android/ui_android.gyp:page_transition_types_java',
         '../ui/android/ui_android.gyp:window_open_disposition_java',
       ],
+      # Enable feedback-directed optimisation for the library when building in
+      # android.
+      'aosp_build_settings': {
+        'LOCAL_FDO_SUPPORT': 'true',
+      },
     }],
     [ 'android_webview_build==1 and use_system_skia==0', {
       # When not using the system skia there are linker warnings about

build/android/android_exports.lst

@@ -10,5 +10,6 @@
   global:
     Java_*_native*;
     JNI_OnLoad;
+    __gcov_*;
   local: *;
 };

skia/skia_common.gypi

@@ -114,6 +114,13 @@
         'SK_ARM_HAS_OPTIONAL_NEON',
       ],
     }],
+
+    # Enable feedback-directed optimisation for skia when building in android.
+    [ 'android_webview_build == 1', {
+      'aosp_build_settings': {
+        'LOCAL_FDO_SUPPORT': 'true',
+      },
+    }],
   ],
 
   'variables': {

third_party/sqlite/sqlite.gyp

@@ -161,6 +161,12 @@
                 '-Wno-pointer-to-int-cast',
               ],
             }],
+            # Enable feedback-directed optimisation for sqlite when building in android.
+            ['android_webview_build == 1', {
+              'aosp_build_settings': {
+                'LOCAL_FDO_SUPPORT': 'true',
+              },
+            }],
           ],
         }],
       ],