Add Link-Time Optimizations support for Android.

build/android/increase_size_for_speed.gypi

Index: build/android/increase_size_for_speed.gypi
diff --git a/build/android/increase_size_for_speed.gypi b/build/android/increase_size_for_speed.gypi
index f5f2d6263322bd53270e1bc38348619e800113dc..4081cd71bfc1f59e58814c344faab2a625349fd0 100644
--- a/build/android/increase_size_for_speed.gypi
+++ b/build/android/increase_size_for_speed.gypi
@@ -18,6 +18,22 @@
               'cflags!': ['-Os'],
               'cflags': ['-O2'],
             }],
+            # Do not merge -Os and -O2 in LTO.
+            # LTO merges all optimization options at link-time. -O2 takes
+            # precedence over -Os. Avoid using LTO simultaneously
+            # on -Os and -O2 parts for that reason.
+            ['use_lto==1', {
+              'cflags!': [
+                '-flto',
+                '-ffat-lto-objects',
+              ],
+            }],
+            ['use_lto_o2==1', {
+              'cflags': [
+                '-flto',
+                '-ffat-lto-objects',
+              ],
+            }],
           ],
         }],
       ],