Fix gamepad mapping for Shield and Xbox controllers

This CL maps trigger axes to bottom shoulder buttons and
trigger buttons to top shoulder buttons for Shield and Xbox
controllers.

BUG=421833

Review URL: https://codereview.chromium.org/704523002

Cr-Commit-Position: refs/heads/master@{#306697}

content/public/android/java/src/org/chromium/content/browser/input/GamepadMappings.java

@@ -75,6 +75,13 @@ class GamepadMappings {
         mappedButtons[CanonicalButtonIndex.RIGHT_TRIGGER] = r1;
     }
 
+    private static void mapTriggerButtonsToTopShoulder(float[] mappedButtons, float[] rawButtons) {
+        float l1 = rawButtons[KeyEvent.KEYCODE_BUTTON_L1];
+        float r1 = rawButtons[KeyEvent.KEYCODE_BUTTON_R1];
+        mappedButtons[CanonicalButtonIndex.LEFT_SHOULDER] = l1;
+        mappedButtons[CanonicalButtonIndex.RIGHT_SHOULDER] = r1;
+    }
+
     private static void mapCommonDpadButtons(float[] mappedButtons, float[] rawButtons) {
         float dpadDown = rawButtons[KeyEvent.KEYCODE_DPAD_DOWN];
         float dpadUp = rawButtons[KeyEvent.KEYCODE_DPAD_UP];
@@ -108,6 +115,13 @@ class GamepadMappings {
         mappedButtons[CanonicalButtonIndex.RIGHT_SHOULDER] = rTrigger;
     }
 
+    private static void mapTriggerAxesToBottomShoulder(float[] mappedButtons, float[] rawAxes) {
+        float lTrigger = rawAxes[MotionEvent.AXIS_LTRIGGER];
+        float rTrigger = rawAxes[MotionEvent.AXIS_RTRIGGER];
+        mappedButtons[CanonicalButtonIndex.LEFT_TRIGGER] = lTrigger;
+        mappedButtons[CanonicalButtonIndex.RIGHT_TRIGGER] = rTrigger;
+    }
+
     private static float negativeAxisValueAsButton(float input) {
         return (input < -0.5f) ? 1.f : 0.f;
     }
@@ -132,10 +146,10 @@ class GamepadMappings {
     private static void mapShieldGamepad(float[] mappedButtons, float[] rawButtons,
             float[] mappedAxes, float[] rawAxes) {
         mapCommonXYABButtons(mappedButtons, rawButtons);
-        mapCommonTriggerButtons(mappedButtons, rawButtons);
+        mapTriggerButtonsToTopShoulder(mappedButtons, rawButtons);
         mapCommonThumbstickButtons(mappedButtons, rawButtons);
         mapCommonStartSelectMetaButtons(mappedButtons, rawButtons);
-        mapTriggerAxexToShoulderButtons(mappedButtons, rawAxes);
+        mapTriggerAxesToBottomShoulder(mappedButtons, rawAxes);
         mapHatAxisToDpadButtons(mappedButtons, rawAxes);
 
         mapXYAxes(mappedAxes, rawAxes);